Add set-version workflow

Author: weswigham

.github/workflows/set-version.yaml

@@ -0,0 +1,45 @@
+name: Set branch version
+
+on:
+  repository_dispatch:
+    types: set-version
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Use node version 12.x
+      uses: actions/setup-node@v1
+      with:
+        node-version: 12.x
+    - uses: actions/checkout@v2
+      with:
+        ref: ${{ github.event.client_payload.branch_name }}
+        fetch-depth: 0
+    # notably, this is essentially the same script as `new-release-branch.yaml` (with fewer inputs), but it assumes the branch already exists
+    # do note that executing the transform below will prevent the `configurePrerelease` script from running on the source, as it makes the
+    # `version` identifier no longer match the regex it uses
+    # required client_payload members:
+    # branch_name - the target branch
+    # package_version - the full version string (eg, `3.9.1-rc` or `3.9.2`)
+    # core_major_minor - the major.minor pair associated with the desired package_version (eg, `3.9` for `3.9.3`)
+    - run: |
+        sed -i -e 's/"version": ".*"/"version": "${{ github.event.client_payload.package_version }}"/g' package.json
+        sed -i -e 's/const versionMajorMinor = ".*"/const versionMajorMinor = "${{ github.event.client_payload.core_major_minor }}"/g' src/compiler/corePublic.ts
+        sed -i -e 's/const versionMajorMinor = ".*"/const versionMajorMinor = "${{ github.event.client_payload.core_major_minor }}"/g' tests/baselines/reference/api/typescript.d.ts
+        sed -i -e 's/const versionMajorMinor = ".*"/const versionMajorMinor = "${{ github.event.client_payload.core_major_minor }}"/g' tests/baselines/reference/api/tsserverlibrary.d.ts
+        sed -i -e 's/const version = .*;/const version = "${{ github.event.client_payload.package_version }}";/g' src/compiler/corePublic.ts
+        npm install
+        gulp LKG
+        npm test
+        git diff
+        git add package.json
+        git add src/compiler/corePublic.ts
+        git add tests/baselines/reference/api/typescript.d.ts
+        git add tests/baselines/reference/api/tsserverlibrary.d.ts
+        git add ./lib
+        git config user.email "[email protected]"
+        git config user.name "TypeScript Bot"
+        git commit -m 'Bump version to ${{ github.event.client_payload.package_version }} and LKG'
+        git push