api [nfc]: Update notif-token routes based on API docs

[gnprice]

When we originally wrote the bindings for these routes, they weren't
yet documented, so we invented our own names for them. Now they are,
so the API docs give canonical names. Switch to those,
and mark the appid parameter required as the docs say.

[gnprice]

Prompted by the initial commits of #948.

[gnprice]

CI failed on 5 unit tests, all in test/model/database_test.dart and looking like this:

❌ /home/runner/work/zulip-flutter/zulip-flutter/test/model/database_test.dart: non-migration tests create account (failed)
  Invalid argument(s): Failed to load dynamic library 'libsqlite3.so': libsqlite3.so: cannot open shared object file: No such file or directory
  dart:ffi                                                        new DynamicLibrary.open
  package:sqlite3/src/ffi/load_library.dart 52:27                 _defaultOpen
  package:sqlite3/src/ffi/load_library.dart 127:12                OpenDynamicLibrary.openSqlite
  package:sqlite3/src/ffi/api.dart 13:39                          sqlite3
  package:drift/native.dart 313:12                                _NativeDelegate.openDatabase
  package:drift/src/sqlite3/database.dart 79:19                   Sqlite3Delegate.open
  package:drift/src/runtime/executor/helpers/engines.dart 431:22  DelegatedDatabase.ensureOpen.<fn>

Seems like an infra issue that's clearly unrelated to this PR.

I'll rerun the check and see if the issue is repeatable. If so, we should adjust our CI setup file to resolve it.

[chrisbobbe]

I'm going to click "Re-run jobs" here:

because it looks like it should succeed now: #999 (comment)

[chrisbobbe]

(Looks like that worked; all checks passed this time.)

[chrisbobbe]

Thanks, LGTM! Merged.