Make CLI (version) configureable

[StefMa]

Currently the CLI version is hardcoded:

SentryProguardGradlePlugin/src/main/kotlin/com/ioki/sentry/proguard/gradle/plugin/tasks/DownloadSentryCliTask.kt

Lines 40 to 51 in e787f19

	private fun findSentryCliDownloadUrl(): String {
	val osName = System.getProperty("os.name").lowercase(Locale.ROOT)
	return when {
	osName.contains("mac") ->
	"https://github.com/getsentry/sentry-cli/releases/download/2.12.0/sentry-cli-Darwin-arm64"
	osName.contains("nix") || osName.contains("nux") || osName.contains("aix") ->
	"https://github.com/getsentry/sentry-cli/releases/download/2.12.0/sentry-cli-Linux-x86_64"
	else -> throw GradleException("We do not support $osName")
	}
	}

We should make it possible that plugin consumers can change the version via extensions (see also #4).

To note:
Updating the version of the CLI might break the uploading in case the CLI parameters change.