* Fixed spotless config for copyright year

* ignore license header files from header lint check

* Add new module for resource-detector support library

* Rname GCPResource -> GCPResourceProvider

* Extract GCPMetadataConfig into support library

* Refactor platform detection from resource provider

* Refactor platform detection to enhance testing

* make EnvironmentVariables package-private

* Add license headers to the newly added files

* Fix spotless style findings

* Remove CloudLocationUtil class

* change attribute map to hold string instead of optional values

* add tests to verify resource attributes mapping

* add javadoc to public classes

* add unit test for ServiceLoader discoverability

* Remove no-args constructor for simplified testing

* Update gradle files to support junit5 testing

* Add missing attribute in GKE mapping

* Add tests for resources-support library

* Update copyright year in GoogleCloudRun.java

* Add missing newline

* Update resource-detector tests to JUnit5

* Remove non-GCP attributes from GKE detection

* Add missing attributes in detected GCE environment

* Update tests for GAE

* Add CLOUD_ACCOUNT_ID to all supported platforms

* Rename support package: detectors -> detection

Support library was using the same package as the detectors library.
This rename would avoid potential conflicts and import issues.

* Undo breaking changes

These breaking chnages can be directly introduced when we contribute the
resource detector upstream. This commit adds classes back and marks them
deprecated to indicate to the users not to depend on them.