feat(express): Introduce Clerk package for Express (#2918)

* feat(express): Introduce @clerk/express [SDK-644]

* chore(express): Apply PR comments

* chore(express,clerk-sdk-node): Cleanup unused deps and files

* Update packages/express/README.md

Co-authored-by: Lennart <lekoarts@gmail.com>

* Update packages/express/LICENSE

Co-authored-by: Lennart <lekoarts@gmail.com>

* Update .changeset/bright-gorillas-crash.md

Co-authored-by: Lennart <lekoarts@gmail.com>

* chore(express): Update dependencies to latest

* chore(express): Replace `protect` with `requireAuth` and add some error handling

* chore(*): Upgrade express playground to use `@clerk/express`

* fix(express): Add tsconfig.lint.json to lint all files

* chore(express): Update docs links

* feat(express): Add tests

* fix(repo): Add core-2 default keys to integrations keys sample json

* chore(express): Address PR comments about docs & links

* chore(express): Rename isAuthInRequest helper to requestHasAuthObject for readability

* chore(express): Refactor clerkMiddleware to support clerkClient param instead of implicit creation

---------

Co-authored-by: Lennart <lekoarts@gmail.com>

Author: dimkl

.changeset/bright-gorillas-crash.md

@@ -0,0 +1,12 @@
+---
+'@clerk/express': patch
+---
+
+Introduce [Express](https://expressjs.com/) specific Clerk SDK called `@clerk/express`. The SDK exposes the following APIs:
+
+- `clerkClient`: Default [`@clerk/backend`](https://clerk.com/docs/references/backend/overview) client initialized from environment variables and used to make backend API requests
+- `clerkMiddleware`: Centralized middleware that authenticates all requests without blocking them (also triggers handshake mechanism)
+- `getAuth`: Utility to retrieve the auth state from a request (requires `clerkMiddleware` to be executed)
+- `requireAuth`: Middleware that returns HTTP 401 response when request is signed-out
+
+Also all the top level exports from `@clerk/backend` are re-exported from `@clerk/express`.

.github/labeler.yml

@@ -12,6 +12,9 @@ clerk-js:
 elements:
   - packages/elements/**
 
+express:
+  - packages/express/**
+
 expo:
   - packages/expo/**
 

.jit/config.yml

@@ -32,3 +32,6 @@ folders:
       - ./**/*.test.ts
   - path: /packages/themes
   - path: /packages/types
+  - path: /packages/express
+    exclude:
+      - ./**/*.test.ts

integration/.keys.json.sample

@@ -10,5 +10,9 @@
   "with-custom-roles": {
     "pk": "",
     "sk": ""
+  },
+  "core-2-all-enabled": {
+    "pk": "",
+    "sk": ""
   }
 }