feat: suppress Maven transfer progress via MAVEN_ARGS by default

Set MAVEN_ARGS to include -ntp (--no-transfer-progress) so Maven invocations
in the job produce cleaner CI logs without download/transfer progress noise.
Add a new optional 'show-download-progress' input (default false); set it to
true to keep the progress output.

The change preserves any existing MAVEN_ARGS value (the flag is appended,
not overwritten) and is idempotent (it won't add the flag twice if -ntp or
--no-transfer-progress is already present). Applies on all platforms; honored
by Maven 3.9.0+ and the Maven Wrapper, and is a no-op for non-Maven builds.

- action.yml: add show-download-progress input
- src/constants.ts: add input + MAVEN_ARGS constants
- src/maven-args.ts: new configureMavenArgs()
- src/setup-java.ts: invoke configureMavenArgs() during setup
- __tests__/maven-args.test.ts: unit tests
- docs/advanced-usage.md: document the behavior and input
- dist: rebuild bundled action

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

action.yml

@@ -75,6 +75,10 @@ inputs:
   mvn-toolchain-vendor:
     description: 'Name of Maven Toolchain Vendor if the default name of "${distribution}" is not wanted. See examples of supported syntax in Advanced Usage file'
     required: false
+  show-download-progress:
+    description: 'Whether Maven should print artifact download/transfer progress to the build log. When "false" (default) the action sets "-ntp" (--no-transfer-progress) in MAVEN_ARGS to produce cleaner logs. Set to "true" to keep the progress output. Has no effect on non-Maven builds.'
+    required: false
+    default: false
 outputs:
   distribution:
     description: 'Distribution of Java that has been installed'