Revise handling of files with local encoding

[jneira]

• Use T.decodeUtf8 + BS.readFile instead of T.readFile #2637 assumes file encoding must be utf8, but almost surely that assumption was present in the codebase before that
• Most users will be using utf8 and there is no issues about this afaik but maybe it worths to give a try using a local encoding (pre and post Use T.decodeUtf8 + BS.readFile instead of T.readFile #2637), verify hls does not work with local encoding and try to detect and warn users about with a lsp alert and noting it explicitly in docs

[Bodigrim]

#2637 assumes file encoding must be utf8, but almost surely that assumption was present in the codebase before that

As I said in #2637, we do not assume anything which is not yet implied by GHC, which requires file encoding to be UTF-8.

[jneira]

Oh, thanks for the info, closing this then