feat: support flag and command deprecations

[mdonnalley]

Support deprecation warnings for flags and commands

Commands

export default class MyCommand extends Command {
  static state = 'deprecated'
}

Warning: The "my command" command has been deprecated.

export default class MyCommand extends Command {
  static state = 'deprecated'
  static deprecationOptions = {
    to: 'my other command"
    version: '2.0.0',
  }
}

Warning: The "my command" command has been deprecated and will be removed in version 2.0.0. Use "my other command" instead.

Flags

export default class MyCommand extends Command {
  static flags = {
    name: Flags.string({
      char: 'n',
      summary: 'Name to print.',
      deprecated: {
        to: 'full-name',
        version: '2.0.0',
      }
    }),
   'full-name': Flags.string({
      summary: 'Name to print.',
    }),
  }
}

Warning: The "name" flag has been deprecated and will be removed in version 2.0.0. Use "full-name" instead.

export default class MyCommand extends Command {
  static flags = {
    name: Flags.string({
      char: 'n',
      summary: 'Name to print.',
      deprecated: true
    }),
  }
}

Warning: The "name" flag has been deprecated.

@W-11836498@

[mshanemc]

since there's only 1 word of difference, it could be consolidated?
formatDeprecationWarning(deprecationType: 'command' | 'flag', item: string, opts: true | Deprecation)

[mshanemc]

1 non-blocking suggestion comment.

can you also put on here what, if anything, needs to be done or should be done for SfdxCommand as a result of this?

Are the deprecations compatible? Does this get overridden in sfdxCommand? Should sfdxCommand remove its code for this and rely directly on oclif's ?

[mshanemc]

+1 for that!