This fix allows for multiple language servers at once which support
workspace commands. This was previously broken as just the first
language server supporting workspace commands was queried when listing
allowed worspace commands.
The fix is in two parts. Firstly, querying all workspace commands from
all language servers available and using them when actually running the
command in `lsp_workspace_command`. Secondly, doing the same in
`completers::lsp_workspace_command` such that completion still works as
expected.
The fix has one remaining issue, which I am unsure how to handle in the
best way possible, but which I also don't think should happen often:
Multiple language servers may register commands with the same name. This
will lead to that command being listed in the popup menu and in the
completion list multiple times, which can be possibly confusing. One
could disambigue them in the popover menu, but I am not sure the same
can be done for completion. When running `lsp-workspace-command` with
parameters, this behavior is "fixed" by displaying an error in that
case. I am unsure if this is the best fix for this issue in that case,
but could not find a better one.