fix: infer tabSize sent in the LSP formattingOptions (#422)

[masonkatz]

Full discussion in issue #422

• go back to inferring the tabSize
• keep indentSize unchanged

I've been running this for several days in Go and Python.

[bbatsov]

Didn't you also say that indentSize is redundant?

[masonkatz]

I believe that indentSize is not used, but may have been at one time.

• tabSize can be found as a variable in the language server .js code (also in the .map file).

• indentSize does not exist in the server .js code -- but it is in the .map file.

• While it is not in the copilot.vim code it does appear in the xcode (also from github) version.

To be conservative I kept it in.

Which makes more sense?

1. take it out
2. add a comment saying it is suspected to be unused

[bbatsov]

Add a comment so we won't forget to investigate this further down the road.

[masonkatz]

PR updated

[bbatsov]

Thanks!