fix(lsp): only send diagnostics from current buffer in code_action() (n…

…eovim#18655)

Fix vim.lsp.buf.(range_)code_action() to only send diagnostics belonging
to the current buffer and not to other files in the workspace.

(cherry picked from commit e3d660e)

Co-authored-by: Fredrik Ekre <ekrefredrik@gmail.com>

runtime/lua/vim/lsp/buf.lua

@@ -595,7 +595,8 @@ function M.code_action(context)
   validate { context = { context, 't', true } }
   context = context or {}
   if not context.diagnostics then
-    context.diagnostics = vim.lsp.diagnostic.get_line_diagnostics()
+    local bufnr = vim.api.nvim_get_current_buf()
+    context.diagnostics = vim.lsp.diagnostic.get_line_diagnostics(bufnr)
   end
   local params = util.make_range_params()
   params.context = context
@@ -621,7 +622,8 @@ function M.range_code_action(context, start_pos, end_pos)
   validate { context = { context, 't', true } }
   context = context or {}
   if not context.diagnostics then
-    context.diagnostics = vim.lsp.diagnostic.get_line_diagnostics()
+    local bufnr = vim.api.nvim_get_current_buf()
+    context.diagnostics = vim.lsp.diagnostic.get_line_diagnostics(bufnr)
   end
   local params = util.make_given_range_params(start_pos, end_pos)
   params.context = context