chore: cursormove refactor

[alanlong9278]

Description

Cursormove refactor.

• Experience
  If pressing ↑ and ↓, cursor should move to previous / following node.
  If cursor is focusing on a node with siblings, pressing ← and → should navigate to siblings.
  If cursor is focusing on 'BotSays' node of a prompt type, pressing ↓ should nav to 'UserAnswers', then pressing → should nav to 'Exceptions'; if focusing on 'Exceptions', pressing ↑ should nav to 'BotSays'

Code Construction

TODO

Unit test

Task Item

closes #1082

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

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

@yeze322 I am a little out of context with this code, so go ahead and review and merge if it is all good.

[yeze322]

@yeze322 I am a little out of context with this code, so go ahead and review and merge if it is all good.

In this PR, we are targeting to fix the cursor move behavior based on old mechanism (node position, not the data structure solution we discussed offline) to make sure the user experience good enough.

Alan and I was working on higher priority tasks yesterday, we will go through this PR together again this week. Now mark it as WIP until we finished.

The new cursor move algorithm is still on top of our todo list but not P0

[lgtm-com]

This pull request introduces 3 alerts and fixes 1 when merging faa8392 into d65ae3b - view on LGTM.com

new alerts:

• 3 for Useless assignment to local variable

fixed alerts:

• 1 for Useless conditional

[yeze322]

After several turns of optimizing the behavior and code structure of 'cursor move', now it has been improved a lot and in a better shape!

Cursor move is a complicated feature which requires many tricky treatments. Current code defined a good up-layer interface and detailed implementation is encapsulated in the calculate folder.

Of course we need further refactoring on calculate folder, but in this PR, alternatively, we can add UT for caculateBySchema and calculateByVector to prove they have correct behaviors.

So we have two remaining things
1 write a simple spec for explaining how it works (with example)
2 unit tests for calculate folder

[cwhitten]

@alanlong9278 this is great work!