Add ALERename (tsserver & LSP), ALEOrganizeImports (tsserver) and auto import support (tsserver) (#2709)

This commit adds support for renaming symbols in tsserver and with LSP tools, and for organising imports with tsserver. Completion results for symbols that can be imported are now suggested if enabled for tsserver completion done via ALE.

test/lsp/test_other_initialize_message_handling.vader

@@ -17,6 +17,7 @@ Before:
   \ 'init_queue': [],
   \ 'capabilities': {
   \   'hover': 0,
+  \   'rename': 0,
   \   'references': 0,
   \   'completion': 0,
   \   'completion_trigger_characters': [],
@@ -100,6 +101,7 @@ Execute(Capabilities should bet set up correctly):
   \   'hover': 1,
   \   'definition': 1,
   \   'symbol_search': 1,
+  \   'rename': 1,
   \ },
   \ b:conn.capabilities
   AssertEqual [[1, 'initialized', {}]], g:message_list
@@ -110,7 +112,7 @@ Execute(Disabled capabilities should be recognised correctly):
   \ 'id': 1,
   \ 'result': {
   \   'capabilities': {
-  \     'renameProvider': v:true,
+  \     'renameProvider': v:false,
   \     'executeCommandProvider': {
   \       'commands': [],
   \     },
@@ -143,6 +145,7 @@ Execute(Disabled capabilities should be recognised correctly):
   \   'hover': 0,
   \   'definition': 0,
   \   'symbol_search': 0,
+  \   'rename': 0,
   \ },
   \ b:conn.capabilities
   AssertEqual [[1, 'initialized', {}]], g:message_list