refactor: centralize lg parsing logic to 'shared' lib

[yeze322]

Description

Closes #1308.
Closes #1659.

Merges all LG related logic to one module in '@bfc/shared'. Prepares for the upcoming lg syntax update.

Where are we parsing lg strings?

• In 'visual -> ObiEditor.ts -> line 52, 92', we parse lg string to extract lg name and node id to perform lg copy.
• In 'visual -> utils -> hooks.ts', we parse lg string to extract lg name (and then invoke lgApi to update template)
• In 'client -> lgUtils.ts', we parse lg string to extract lg name
• In 'packages/lib -> indexers -> dialogIndexer.ts', we parse lg string to extract lg name
• In 'form -> TableField -> line 100', extract lg name out of string (should be coverd in another PR which focuses on shellApi refinement)
• In 'form -> LgEditorWidget.tsx -> line 35~52, line 102', construct a lg id.
• In 'form -> LgEditorWidget.tsx' -> line 18~22, handle lgText.

How we understand LG strings

  1. LgText
  {
      "activity": "....", // LgText
      "prompt": "....", // LgText
      "invalidPrompt": "..." // LgText
  }

  2. LgTemplateRef
  '[bfdactivity-1234]'
  '[greeting]'
  '[greeting(1)]'

  3. LgTemplateName
  'bfdactivity-1234' in '[bfdactivity-1234]'
  'greeting' in '[greeting(1)]'

  4. LgMetaData (Composer-only, can be converted to LgTemplateName)
  'bfdactivity-1234' => { type: 'activity', designerId: '1234' } // LgMetaData
  'greeting' => NO meta data since its not created by Composer

Task Item

Closes #1308

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code refactor (non-breaking change which improve code quality, clean up, add tests, etc)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Doc update (document update)

Checklist

• I have added tests that prove my fix is effective or that my feature works
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have functionally tested my change

Screenshots

Please include screenshots or gifs if your PR include UX changes.

[yeze322]

We can leverage the 'optional chaining' feature in ts 3.7. LgTemplateRef.parse(x)?.name

[a-b-r-o-w-n]

#1686

[yeze322]

copyLgTemplate will be defined as copyLgText in my following PR. Targets to hide LG concepts from visual editor (and Form Editor), will inject a synthesized lg api from Shell level.

[yeze322]

deleteLgTemplates will be defined as deleteLgText. See my next comments on copyLgTemplate

[boydc2014]

LGTM, but let's wait a little bit until @cwhitten and @a-b-r-o-w-n can have a chance to look at. Also, if LSP is also good to go, let's merge LSP first.