fix: update API code to use Axios instances (#13029)

* fix: update API code to use Axios instance

* docs: fix typo

* fix: update all global axios imports to use Coder instance

* fix: remove needless import

* fix: update import order

* refactor: rename coderAxiosInstance to axiosInstance

* docs: update variable reference in FE contributing docs

docs/contributing/frontend.md

@@ -152,7 +152,7 @@ example below:
 export const getAgentListeningPorts = async (
   agentID: string,
 ): Promise<TypesGen.ListeningPortsResponse> => {
-  const response = await axios.get(
+  const response = await axiosInstance.get(
     `/api/v2/workspaceagents/${agentID}/listening-ports`,
   );
   return response.data;