Reorganize server files and address TODO comments

Changes:
- Remove unneeded dependencies from package.json
- Remove unneeded async build() methods from services
    - Use constructor as often as possible
- Rename and move storage services for clarity
    - creds.ts -> accounts.ts, and creds.json -> accounts.json
    - admin-config.ts -> admin-account.ts
    - vault.ts -> signing-keys.ts
- Rename ws.ts to websocket-server.ts for clarity and consistency
- Make WebSocketServer initialize using constructor and bind server upgrade to WebSocketServer.upgrade
- Remove unused send-account-message endpoint from account-router.ts
- Set issuer and audience claims for JWT
- Create new utils/jwt.ts file to remove code duplication for JWT signing and verifying
- Delete utils.ts and merge it with jami-swig.ts
- Handle potentially undefined types in jami-swig.ts
- Replace hard to read one-liners with functions in jami-swig.ts
- Rename types in jami-swig.ts for consistency with daemon
- Remove handled/answered TODO comments
- Remove TODO comment about using .env for jamid.node as it does not work for require()

GitLab: #87
Change-Id: I1e5216ffa79ea34dd7e9b61540fb7e37d1f66c9f
diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index 2d47543..a69ad04 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -76,6 +76,7 @@
     '@typescript-eslint/ban-ts-comment': 'off',
     '@typescript-eslint/no-empty-function': 'off',
     '@typescript-eslint/no-explicit-any': 'off',
+    '@typescript-eslint/no-non-null-assertion': 'off',
     '@typescript-eslint/no-unused-vars': 'off',
     camelcase: 'error',
     eqeqeq: ['error', 'smart'],