#2132 Use an on-init callback for all LSP logic

test/lsp/test_did_save_event.vader

@@ -34,16 +34,19 @@ Before:
   \ })
   let g:ale_linters = {'foobar': ['dummy_linter']}
 
-  function! ale#lsp_linter#StartLSP(buffer, linter) abort
+  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let g:conn_id = ale#lsp#Register('executable', '/foo/bar', {})
     call ale#lsp#MarkDocumentAsOpen(g:conn_id, a:buffer)
-
-    return {
+    let l:details = {
     \ 'buffer': a:buffer,
     \ 'connection_id': g:conn_id,
     \ 'project_root': '/foo/bar',
     \ 'language_id': 'foobar',
     \}
+
+    call a:Callback(a:linter, l:details)
+
+    return 1
   endfunction
 
   " Replace the Send function for LSP, so we can monitor calls to it.
@@ -61,6 +64,7 @@ After:
   unlet! b:ale_enabled
   unlet! b:ale_linters
   unlet! g:message_list
+  unlet! b:ale_save_event_fired
 
   delfunction LanguageCallback
   delfunction ProjectRootCallback