Add clipboard provider configuration (#8826)

This change adds the `clipboard-provider` setting to the `editor` section
of configuration.

This option can have values of:
- `none`
(on windows only)
- `windows` (use native windows clipboard)
- `pasteboard` (use pbcopy/pbpaste)
(on neiter of the above)
- `wayland`
- `x-clip`
- `x-sel`
- `win-32-yank` (for wsl)
- `termux`
- `tmux`
(on all targets with "term")
- `termcode` (osc codes)
- `custom` (see below for the configuration)

Note for a custom provider the configurations should look like:
```toml
[editor.clipboard-provider.custom]
yank = { command = "cat",  args = ["test.txt"] }
paste = { command = "tee",  args = ["test.txt"] }
primary-yank = { command = "cat",  args = ["test-primary.txt"] } # optional
primary-paste = { command = "tee",  args = ["test-primary.txt"] } # optional
```

This can be configured at runtime with the usual:
```
set clipboard-provider term
```
Note: I was unable to work out a syntax expression for setting a `custom`
provider at runtime. In my opinion this is probably a fine limitation to
have but I am curious if there is a correct way I couldn't work out.

This ports over the previous provider selection logic so hopefully the
same default behaviour should apply.

I updated the health command to reflect the provider.
Note: this required reading the user configurations within the health command
which warrants discussion as this seems to not have been done before.

This is my first contribution, I am a C++ developer by profession and
a rust hobyist at best so nits and style updates very welcome.

book/src/editor.md

@@ -52,6 +52,30 @@
 | `indent-heuristic` | How the indentation for a newly inserted line is computed: `simple` just copies the indentation level from the previous line, `tree-sitter` computes the indentation based on the syntax tree and `hybrid` combines both approaches. If the chosen heuristic is not available, a different one will be used as a fallback (the fallback order being `hybrid` -> `tree-sitter` -> `simple`). | `hybrid`
 | `jump-label-alphabet` | The characters that are used to generate two character jump labels. Characters at the start of the alphabet are used first. | `"abcdefghijklmnopqrstuvwxyz"`
 | `end-of-line-diagnostics` | Minimum severity of diagnostics to render at the end of the line. Set to `disable` to disable entirely. Refer to the setting about `inline-diagnostics` for more details | "disable"
+| `clipboard-provider` | Which API to use for clipboard interaction. One of `pasteboard` (MacOS), `wayland`, `x-clip`, `x-sel`, `win-32-yank`, `termux`, `tmux`, `windows`, `termcode`, `none`, or a custom command set. | Platform and environment specific. |
+
+### `[editor.clipboard-provider]` Section
+
+Helix can be configured wither to use a builtin clipboard configuration or to use
+a provided command.
+
+For instance, setting it to use OSC 52 termcodes, the configuration would be:
+```toml
+[editor]
+clipboard-provider = "termcode"
+```
+
+Alternatively, Helix can be configured to use arbitary commands for clipboard integration:
+
+```toml
+[editor.clipboard-provider.custom]
+yank = { command = "cat",  args = ["test.txt"] }
+paste = { command = "tee",  args = ["test.txt"] }
+primary-yank = { command = "cat",  args = ["test-primary.txt"] } # optional
+primary-paste = { command = "tee",  args = ["test-primary.txt"] } # optional
+```
+
+For custom commands the contents of the yank/paste is communicated over stdin/stdout.
 
 ### `[editor.statusline]` Section
 

helix-stdx/Cargo.toml

@@ -15,6 +15,7 @@ homepage.workspace = true
 dunce = "1.0"
 etcetera = "0.8"
 ropey = { version = "1.6.1", default-features = false }
+serde = { version = "1.0" }
 which = "6.0"
 regex-cursor = "0.1.4"
 bitflags = "2.6"

helix-term/src/health.rs

@@ -1,10 +1,10 @@
+use crate::config::{Config, ConfigLoadError};
 use crossterm::{
     style::{Color, Print, Stylize},
     tty::IsTty,
 };
 use helix_core::config::{default_lang_config, user_lang_config};
 use helix_loader::grammar::load_runtime_file;
-use helix_view::clipboard::get_clipboard_provider;
 use std::io::Write;
 
 #[derive(Copy, Clone)]
@@ -53,7 +53,6 @@ pub fn general() -> std::io::Result<()> {
     let lang_file = helix_loader::lang_config_file();
     let log_file = helix_loader::log_file();
     let rt_dirs = helix_loader::runtime_dirs();
-    let clipboard_provider = get_clipboard_provider();
 
     if config_file.exists() {
         writeln!(stdout, "Config file: {}", config_file.display())?;
@@ -92,7 +91,6 @@ pub fn general() -> std::io::Result<()> {
             writeln!(stdout, "{}", msg.yellow())?;
         }
     }
-    writeln!(stdout, "Clipboard provider: {}", clipboard_provider.name())?;
 
     Ok(())
 }
@@ -101,8 +99,19 @@ pub fn clipboard() -> std::io::Result<()> {
     let stdout = std::io::stdout();
     let mut stdout = stdout.lock();
 
-    let board = get_clipboard_provider();
-    match board.name().as_ref() {
+    let config = match Config::load_default() {
+        Ok(config) => config,
+        Err(ConfigLoadError::Error(err)) if err.kind() == std::io::ErrorKind::NotFound => {
+            Config::default()
+        }
+        Err(err) => {
+            writeln!(stdout, "{}", "Configuration file malformed".red())?;
+            writeln!(stdout, "{}", err)?;
+            return Ok(());
+        }
+    };
+
+    match config.editor.clipboard_provider.name().as_ref() {
         "none" => {
             writeln!(
                 stdout,