feat!: v4 release (#871)

Any advanced configuration should be done via a
release-please-config.json.

Fixes #859
Fixes #858
Fixes #857
Fixes #852

feat!: remove most configuration options in favor of manifest
configuration to configure the release-please-action
refactor!: rewrite in typescript
feat!: remove command option in favor of setting `release-type` and
`skip-github-release`/`skip-github-pull-request`
feat!: run on node20
deps!: upgrade release-please to v16

tsconfig.json

@@ -0,0 +1,16 @@
+{
+  "extends": "./node_modules/gts/tsconfig-google.json",
+  "compilerOptions": {
+    "allowSyntheticDefaultImports": true,
+    "rootDir": ".",
+    "outDir": "build",
+    "resolveJsonModule": true
+  },
+  "include": [
+    "src/*.ts",
+    "src/**/*.ts",
+    "test/*.ts",
+    "test/**/*.ts",
+    "system-test/*.ts"
+  ]
+}