Powershell formatting is not supported

[r-darwish]

Describe the bug
lsp-format-buffer does not work in Powershell even though the server supports formatting

To Reproduce
Run lsp-format-buffer in a Powershell buffer

Expected behavior
Formatting should work like in Visual Studio Code

Which Language Server did you use
Powershell

OS
macOS

Error callstack

Debugger entered--Lisp error: (lsp-capability-not-supported "documentFormattingProvider")
  signal(lsp-capability-not-supported ("documentFormattingProvider"))
  (cond ((or (lsp--capability "documentFormattingProvider") (lsp--registered-capability "textDocument/formatting")) (let ((edits (lsp-request "textDocument/formatting" (lsp--make-document-formatting-params)))) (lsp--apply-formatting edits))) ((or (lsp--capability "documentRangeFormattingProvider") (lsp--registered-capability "textDocument/rangeFormatting")) (save-restriction (widen) (lsp-format-region (point-min) (point-max)))) (t (signal (quote lsp-capability-not-supported) (list "documentFormattingProvider"))))
  lsp-format-buffer()
  funcall-interactively(lsp-format-buffer)
  call-interactively(lsp-format-buffer record nil)
  command-execute(lsp-format-buffer record)
  execute-extended-command(nil "lsp-format-buffer" "lsp-format-bu")
  funcall-interactively(execute-extended-command nil "lsp-format-buffer" "lsp-format-bu")
  call-interactively(execute-extended-command nil nil)
  command-execute(execute-extended-command)

[yyoncho]

@kiennq willing to take a look?

[kiennq]

Powershell language server PSES is really tricky, it declares that it doesn't support document formatting in capabilities.
However, client can still manually request for it.
PowerShell/PowerShellEditorServices#516

[yyoncho]

we might implement patch like adf5ac5 (this commit removes the patch).

[kiennq]

we might implement patch like adf5ac5 (this commit removes the patch).

Nice, I've created a PR for this

[r-darwish]

For reference: #1215