[LSP] auto-suggestion for template name/body should be meaningful

[hibrenda]

Is your feature request related to a problem? Please describe.
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Describe the solution you'd like
Editing in LG all up view, when you type template name/body, it will auto suggest lots of irrelevant info .

Describe alternatives you've considered

• For template name, should not auto-suggest or should auto-suggest based on the context
  eg. list out the template name during template editing , this could help user to avoid duplicate name definition across different dialog.
• For body editing, only auto suggest pre-built function and the predefined template name to make the LG editing more productive.

Additional context
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[sangwoohaan]

I think there are three micro-contexts here

1. Creating a new template: start with #
2. Referring to a template or a property: @{
3. Prebuilt function: Anytime

1. should suggest nothing, 2) would only suggest other templates, then 3) suggests all the prebuilt functions(not templates). Would this make sense? @cwhitten @a-b-r-o-w-n

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

3 would only make since in a template body I believe. Other than that, this makes sense.

[sangwoohaan]

Ok, that makes sense. Could we also suggest known properties like dialog.XXX after @{? Would this potentially cause runtime errors?

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

We should be able to do that eventually. The language server work should enable that, but I'm not sure what's required to do so.

[zhixzhan]

In language server, we can recognize current context, and return proper suggestion list. I will take this