feat: show aliasOf if applicable

[mdonnalley]

• Show aliasOf if provided command is an alias of another command
• Enable --json and return JSON output
• unfancy tests

Fixes #515
@W-14774252@

[cristiand391]

QA notes:

✅ can resolve alias -> command, both topic separator and quotes:

sf which 'force:auth:list'
sf which force:auth:list
sf which force auth list
sf which 'force:auth:list'

// all return:

 ›   Warning: @oclif/plugin-which is a linked ESM module and cannot be auto-transpiled. Existing compiled source
 ›   will be used instead.
=== force:auth:list

aliasOf: org list auth
plugin:  @salesforce/plugin-auth

✅ JSON flag works, also tested with possible quoted/non-quoted ids above

{
  "plugin": "@salesforce/plugin-auth",
  "aliasOf": "org list auth"
}

{
  "plugin": "@salesforce/plugin-auth"
}