Add exclude and additional option to AssembleDownstreamDocumentation

[MichalMaler]

This is backport of https://github.com/quarkusio/quarkus/pull/38082/files
Original PR made by @maxandersen .

[quarkus-bot]

Failing Jobs - Building 67ee5fb

Status	Name	Step	Failures	Logs	Raw logs	Build scan
✔️	Gradle Tests - JDK 11					🚧
✖	Gradle Tests - JDK 11 Windows	Build	Failures	Logs	Raw logs	🚧

Full information is available in the Build summary check run.

Failures

⚙️ Gradle Tests - JDK 11 Windows #

- Failing: integration-tests/gradle 

📦 integration-tests/gradle

✖ io.quarkus.gradle.CustomManifestArgumentsTest.shouldContainsSpecificManifestProperty line 37 - More details - Source on GitHub

java.lang.AssertionError: 

Expecting actual not to be null
	at io.quarkus.gradle.CustomManifestArgumentsTest.shouldContainsSpecificManifestProperty(CustomManifestArgumentsTest.java:37)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)