feat(cli): prefer project-local tools

Increases the utility of the global d2 tool for developers by preferring
the version of the CLI tool that is installed over the globally bundled
one.

Before this change these two commands run in the same project can yield
different results:

    d2 style check          # global
    yarn d2-style check     # local

After the change, they will both use the local version:

    d2 style check          # local
    yarn d2-style check     # local

Jira-ticket-key: CLI-68
Jira-ticket-URL: https://jira.dhis2.org/browse/CLI-68

packages/main/src/index.js

@@ -1,13 +1,35 @@
-const { namespace } = require('@dhis2/cli-helpers-engine')
+const path = require('path')
+const {
+    namespace,
+    findProjectRoot,
+    reporter,
+} = require('@dhis2/cli-helpers-engine')
+
+function load(tool) {
+    const root = findProjectRoot()
+    const paths = root ? [path.resolve(root, 'node_modules')] : []
+
+    try {
+        const resolved = require.resolve(tool, {
+            paths,
+        })
+
+        reporter.debug(`Loading tool from: ${resolved}`)
+        return require(resolved)
+    } catch (err) {
+        reporter.debug(`Loading tool from: ${tool}`)
+        return require(tool)
+    }
+}
 
 const command = namespace('d2', {
     desc: 'DHIS2 CLI',
     builder: yargs => {
-        yargs.command(require('@dhis2/cli-app'))
-        yargs.command(require('@dhis2/cli-cluster'))
-        yargs.command(require('@dhis2/cli-create'))
-        yargs.command(require('@dhis2/cli-style').command)
-        yargs.command(require('@dhis2/cli-utils'))
+        yargs.command(load('@dhis2/cli-app'))
+        yargs.command(load('@dhis2/cli-cluster'))
+        yargs.command(load('@dhis2/cli-create'))
+        yargs.command(load('@dhis2/cli-style').command)
+        yargs.command(load('@dhis2/cli-utils'))
         yargs.commandDir('commands')
     },
 })