add experimental https support to next dev (#54016)

This adds an `--experimental-https` flag to `next dev` which will generate a self-signed certificate via [mkcert](https://github.com/FiloSottile/mkcert) and use it for the dev server.

also supports passing in pre-existing certs via `--experimental-https-cert` and `--experimental-https-key`

x-ref: https://github.com/vercel/next.js/discussions/33768 https://github.com/vercel/next.js/discussions/10935

test/development/experimental-https-server/https-server.provided-key.test.ts

@@ -0,0 +1,29 @@
+import { createNextDescribe } from 'e2e-utils'
+import https from 'https'
+import { renderViaHTTP } from 'next-test-utils'
+
+createNextDescribe(
+  'experimental-https-server (provided certificate)',
+  {
+    files: __dirname,
+    startCommand:
+      'yarn next dev --experimental-https --experimental-https-key ./certificates/localhost-key.pem --experimental-https-cert ./certificates/localhost.pem',
+  },
+  ({ next }) => {
+    const agent = new https.Agent({
+      rejectUnauthorized: false,
+    })
+
+    it('should successfully load the app in app dir', async () => {
+      expect(next.url).toInclude('https://')
+      const html = await renderViaHTTP(next.url, '/1', undefined, { agent })
+      expect(html).toContain('Hello from App')
+    })
+
+    it('should successfully load the app in pages dir', async () => {
+      expect(next.url).toInclude('https://')
+      const html = await renderViaHTTP(next.url, '/2', undefined, { agent })
+      expect(html).toContain('Hello from Pages')
+    })
+  }
+)