Add primitive workaround to ignore KSP generated sources #385

Job	Run time
provide-agp-version-matrix	2s
[ubuntu-latest] build plugin	5m 25s
[windows-latest] build plugin	11m 40s
[ubuntu-latest] Gradle: current, Java: 17	1m 24s
[ubuntu-latest] Gradle: current, Java: 20	1m 24s
[ubuntu-latest] Gradle: release-candidate, Java: 17	1m 32s
[ubuntu-latest] Gradle: release-candidate, Java: 20	1m 36s
[windows-latest] Gradle: current, Java: 17	3m 21s
[windows-latest] Gradle: current, Java: 20	2m 36s
[windows-latest] Gradle: release-candidate, Java: 17	2m 48s
[windows-latest] Gradle: release-candidate, Java: 20	2m 59s
[ubuntu-latest] Gradle: 7.6, Java: 11	1m 48s
[windows-latest] Gradle: 7.6, Java: 11	5m 34s
[ubuntu-latest] Gradle: 8.0.2, Java: 17	1m 26s
[windows-latest] Gradle: 8.0.2, Java: 17	3m 58s
[android] Gradle: current, Java: 20, AGP: 8.1.1	1m 44s
[android] Gradle: current, Java: 20, AGP: 8.3.0-alpha04	2m 51s
[android] Gradle: release-candidate, Java: 20, AGP: 8.1.1	1m 35s
[android] Gradle: release-candidate, Java: 20, AGP: 8.3.0-alpha04	2m 23s
	56m 6s

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