ci: Airlock settings files

How to run the build with Airlock:

```
mvn --settings .mvn/settings.xml clean install -DskipTests
```

Author: suztomo

.mvn/extensions.xml

@@ -0,0 +1,8 @@
+<extensions xmlns="http://maven.apache.org/EXTENSIONS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+            xsi:schemaLocation="http://maven.apache.org/EXTENSIONS/1.0.0 http://maven.apache.org/xsd/core-extensions-1.0.0.xsd">
+    <extension>
+        <groupId>com.google.cloud.artifactregistry</groupId>
+        <artifactId>artifactregistry-maven-wagon</artifactId>
+        <version>2.2.4</version>
+    </extension>
+</extensions>

.mvn/settings.xml

@@ -0,0 +1,11 @@
+<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 https://maven.apache.org/xsd/settings-1.0.0.xsd">
+    <mirrors>
+        <mirror>
+            <id>mirror-of-all</id>
+            <name>Airlock Maven 3P Trusted</name>
+            <url>artifactregistry://us-maven.pkg.dev/artifact-foundry-prod/maven-3p-trusted</url>
+            <mirrorOf>*</mirrorOf>
+        </mirror>
+    </mirrors>
+</settings>

.mvn/settings_bootstrap.xml

@@ -0,0 +1,19 @@
+<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 https://maven.apache.org/xsd/settings-1.0.0.xsd">
+
+    <!-- This will ensure that all requests go through ar - but requires that we have an updated token in the auth section.
+        That token only lasts an hour.
+        To update token:
+           export ARTIFACT_REGISTRY_TOKEN=$(gcloud auth print-access-token)
+    -->
+
+    <mirrors>
+        <mirror>
+            <id>mirror-of-all</id>
+            <name>AR Maven Central mirror</name>
+            <url>https://repo1.maven.org/maven2</url>
+            <mirrorOf>*</mirrorOf>
+        </mirror>
+    </mirrors>
+
+</settings>