Remove building and signing XPI file

[vitonsky]

Since we updated web-ext package, now we should specify addon id in manifest instead of provide it with flag for command. More details here: mozilla/web-ext#3124

As result, we have problem when build a release:

Run mkdir ./AMO
  mkdir ./AMO
  npx web-ext sign --api-key "$AMO_KEY" --api-secret "$AMO_SECRET" --id "{e3fc2d33-09fc-4fe8-9331-d0a464698035}" --source-dir ./firefox --artifacts-dir ./AMO
  mv AMO/*.xpi AMO/linguist.xpi
  shell: /usr/bin/bash -e {0}
  env:
    AMO_KEY: ***
    AMO_SECRET: ***
  
web-ext sign
Sign the extension so it can be installed in Firefox
Options:
      --version             Show version number  [boolean]
  -s, --source-dir          Web extension source directory.  [string] [required] [default: "/home/runner/work/linguist/linguist/build"]
  -a, --artifacts-dir       Directory where artifacts will be saved.  [string] [required] [default: "/home/runner/work/linguist/linguist/build/web-ext-artifacts"]
  -v, --verbose             Show verbose output  [boolean]
  -i, --ignore-files        A list of glob patterns to define which files should be ignored. (Example: --ignore-files=path/to/first.js path/to/second.js "**/*.log")  [array]
      --no-input            Disable all features that require standard input  [boolean]
  -c, --config              Path to a CommonJS config file to set option defaults  [string]
      --config-discovery    Discover config files in home directory and working directory. Disable with --no-config-discovery.  [boolean] [default: true]
      --amo-base-url        Submission API URL prefix  [string] [required] [default: "https://addons.mozilla.org/api/v5/"]
      --api-key             API key (JWT issuer) from addons.mozilla.org  [string] [required]
      --api-secret          API secret (JWT secret) from addons.mozilla.org  [string] [required]
      --api-proxy           Use a proxy to access the signing API. Example: https://yourproxy:6000  [string]
      --timeout             Number of milliseconds to wait before giving up  [number]
      --approval-timeout    Number of milliseconds to wait for approval before giving up. Set to 0 to disable waiting for approval. Fallback to `timeout` if not set.  [number]
      --channel             The channel for which to sign the addon. Either 'listed' or 'unlisted'.  [string] [required]
      --amo-metadata        Path to a JSON file containing an object with metadata to be passed to the API. See https://addons-server.readthedocs.io/en/latest/topics/api/addons.html for details.  [string]
      --upload-source-code  Path to an archive file containing human readable source code of this submission, if the code in --source-dir has been processed to make it unreadable. See https://extensionworkshop.com/documentation/publish/source-code-submission/ for details.  [string]
  -h, --help                Show help  [boolean]
Unknown argument: id
Error: Process completed with exit code 1.

As temporary solution, we may remove building XPI file for serve a standalone addon.

Later we may add a specific target firefox-standalone, that will patch manifest file and add "browser_specific_settings": {"gecko": {"id": "{e3fc2d33-09fc-4fe8-9331-d0a464698035}"}}

[vitonsky]

Or, we may introduce additional target instead

[pointydev]

Will XPI files return to releases? I was wanting to test v6 without having to wait for the AMO release, but am not particularly thrilled about loading it unpacked.

[vitonsky]

Will XPI files return to releases? I was wanting to test v6 without having to wait for the AMO release, but am not particularly thrilled about loading it unpacked.

Actually we still build XPI, PR #448 just add overrides for manifest of standalone version.

File did not been present in release, because problems in CI pipeline. Now i've attached XPI file on release page