Support multiple LSP based completion provider

[anthonykim1]

Coming from: #241167

With #243528 providing support for Python LSP provider in terminal suggest, we should continue making effort towards supporting more lsp completion provider.

Easiest would be starting from pwsh, then potentially for node, julia, etc.

/cc @meganrogge @Tyriar

[anthonykim1]

Moving this out of milestone until #258137 (review)