Feature: Support closing dialog windows (#233)

Supports closing dialogs in development. Upgrades gas-client to 1.2.0 and uses new API here: Add scriptHostFunctions for google.script.host gas-client#36
Example button to close dialog in Bootstrap sample
Updates integration tests

.github/workflows/integration-tests-basic.yaml

@@ -9,9 +9,9 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-12, macos-13, windows-2022]
+        os: [macos-13, windows-2022]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
-        node-version: [18, 20]
+        node-version: [20]
     timeout-minutes: 8
     steps:
       - uses: actions/checkout@v4

.github/workflows/integration-tests-extended.yaml

@@ -9,9 +9,9 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-12, macos-13, windows-2022]
+        os: [macos-13, windows-2022]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
-        node-version: [18, 20]
+        node-version: [20]
     timeout-minutes: 11
     steps:
       - uses: actions/checkout@v4