test/lsp: ensure linter name is set

All linters should have a name variable set in their dictionary, and
code should be able to rely on that. Fix this test such that its example
linter contains a name entry.

test/lsp/test_lsp_command_formatting.vader

@@ -17,6 +17,7 @@ Execute(Command formatting should be applied correctly for LSP linters):
   call ale#lsp_linter#StartLSP(
   \ bufnr(''),
   \ {
+  \   'name': 'linter',
   \   'language_callback': {-> 'x'},
   \   'project_root_callback': {-> '/foo/bar'},
   \   'lsp': 'stdio',