Auto-compile linked plugins

[mdonnalley]

Register ts-node for linked plugins so that developers don't have to compile their plugin before running it

More context: forcedotcom/cli#1664
@W-12652231@

Testing

• yarn link @oclif/core in sfdx-cli
• cd to oclif/plugin-plugins
  • run sfdx plugins link
  • run rm -rf lib/
• cd to sfdx-cli
  • bin/dev plugins
  • bin/run plugins
  • bin/dev version
  • bin/run version
• cd to oclif/plugin-plugins
  • run yarn build
• cd to sfdx-cli
  • bin/dev plugins
  • bin/run plugins
  • bin/dev version
  • bin/run version

[cristiand391]

QA notes:

✅ plugin compiled by ts-node (rmrf lib, updated command, see update after running it)
✅ oclif/ts-node ignores lib folder in plugin (re-compiles at runtime even if I already ran tsc before.)
✅ JS plugin (no tsconfig file), running command just throws not found.

ts-node:
I added some code to print paths in oclif/core to see what ts-node was loading it, see results:

1. ts-node as plugin devDep
   plugin-commands has ts-node as a [devDep](https://github.com/oclif/plugin-commands/blob/main/package.json#L29.
   when loading ts-node, oclif uses the ts-node in the plugin's node_modules folder:

➜  sfdx-cli git:(main) ✗ ./bin/run commands
ROOT: /Users/cdominguez/code/gh/oclif/plugin-commands
__dirname: /Users/cdominguez/code/gh/oclif/core/lib/config
tsNodePath: /Users/cdominguez/code/gh/oclif/plugin-commands/node_modules/ts-node/dist/index.js
 Command                                    Summary
...

2. plugin doesn't have ts-node dep
   For this I used plugin-plugins, removed ts-node from devDeps and then linked it.
   oclif loads ts-node from @oclif/core:

➜  sfdx-cli git:(main) ✗ ./bin/run plugins
ROOT: /Users/cdominguez/code/gh/oclif/plugin-plugins
__dirname: /Users/cdominguez/code/gh/oclif/core/lib/config
tsNodePath: /Users/cdominguez/code/gh/oclif/core/node_modules/ts-node/dist/index.js
@oclif/plugin-plugins 2.3.2 (link) /Users/cdominguez/code/gh/oclif/plugin-plugins

✅ Works on Windows, in the debug logs I can see ts-node gets a valid win path to the linked plugin.