feat(diagnostic)!: deprecate format as a table

runtime/doc/news.txt

@@ -28,6 +28,8 @@ DIAGNOSTICS
   (deprecated in Nvim 0.10 |deprecated-0.10|).
 • The legacy signature of |vim.diagnostic.enable()| (deprecated in Nvim 0.10
   |deprecated-0.10|) is no longer supported.
+• `vim.diagnostic.Opts.Status.format` no longer accepts the table mapping
+  from severity to text. Use `vim.diagnostic.Opts.Signs.text` instead.
 
 EDITOR
 

test/functional/lua/diagnostic_spec.lua

@@ -4219,11 +4219,11 @@ describe('vim.diagnostic', function()
       )
     end)
 
-    it('uses text from diagnostic.config().status.format[severity]', function()
+    it('uses text from diagnostic.config().signs.text[severity]', function()
       local result = exec_lua(function()
         vim.diagnostic.config({
-          status = {
-            format = {
+          signs = {
+            text = {
               [vim.diagnostic.severity.ERROR] = '⨯',
               [vim.diagnostic.severity.WARN] = '⚠︎',
             },