Add property to override lint version (#767)

This allows us to specify it programmatically and source our version
catalogs rather than only statically in `gradle.properties`

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slack-plugin/src/main/kotlin/slack/gradle/SlackProperties.kt

@@ -291,6 +291,13 @@ internal constructor(
   public val lintIgnoreTestSources: Boolean
     get() = booleanProperty("sgp.lint.ignoreTestSources", false)
 
+  /**
+   * Flag to control which agp version should be used for lint. Optional. Value should be a version
+   * key in `libs.versions.toml`,
+   */
+  public val lintVersionOverride: String?
+    get() = optionalStringProperty("sgp.lint.agpVersion")
+
   /**
    * Flag to indicate whether this project is a test library (such as test utils, test fixtures,
    * etc).

slack-plugin/src/main/kotlin/slack/gradle/SlackVersions.kt

@@ -76,6 +76,8 @@ internal class SlackVersions(val catalog: VersionCatalog) {
   val robolectric: String?
     get() = getOptionalValue("robolectric").orElse(null)
 
+  fun lookupVersion(key: String) = getOptionalValue(key)
+
   val bundles = Bundles()
 
   inner class Bundles {

slack-plugin/src/main/kotlin/slack/gradle/lint/LintTasks.kt

@@ -145,6 +145,11 @@ internal object LintTasks {
     onProjectSkipped: (String, String) -> Unit,
   ) =
     androidExtension.finalizeDsl { extension ->
+      slackProperties.lintVersionOverride?.let {
+        val lintVersion = slackProperties.versions.lookupVersion(it)
+        extension.experimentalProperties["android.experimental.lint.version"] = lintVersion
+      }
+
       log("Applying ciLint to Android project")
 
       log(