Provide default value for Compose version for Gradle plugin

There are two versions used in the Gradle plugin:
* The version of the plugin itself;
* The version of Compose dependency used by the plugin.

On CI both versions are set to the same value specific to the build.
However, locally using 0.1.0-SNAPSHOT for the Compose version is inconvenient,
because we don't publish 0.1.0-SNAPSHOT anywhere.
Even if it existed, a moving version is not convenient for using in tests.

This commit changes version handling:
* The version of Compose is set via `compose.version` Gradle property
to the latest stable version, unless overridden by
`COMPOSE_GRADLE_PLUGIN_COMPOSE_VERSION` env. var.
* The version of the plugin is set via `deploy.version`
Gradle property to 0.1.0-SNAPSHOT,
unless overridden by `COMPOSE_GRADLE_PLUGIN_VERSION` env. var

gradle-plugins/buildSrc/src/main/kotlin/BuildProperties.kt

@@ -7,8 +7,9 @@ object BuildProperties {
     const val website = "https://jetbrains.org/compose"
     const val vcs = "https://github.com/JetBrains/compose-jb"
     fun composeVersion(project: Project): String =
-        project.findProperty("compose.version") as? String
+        System.getenv("COMPOSE_GRADLE_PLUGIN_COMPOSE_VERSION")
-            ?: System.getenv("COMPOSE_GRADLE_PLUGIN_COMPOSE_VERSION")
+            ?: project.findProperty("compose.version") as String
-            ?: "0.1.0-SNAPSHOT"
+    fun deployVersion(project: Project): String =
-    fun deployVersion(project: Project): String = System.getenv("COMPOSE_GRADLE_PLUGIN_VERSION") ?: composeVersion(project)
+        System.getenv("COMPOSE_GRADLE_PLUGIN_VERSION")
+            ?: project.findProperty("deploy.version") as String
 }

gradle-plugins/gradle.properties

@@ -1,4 +1,13 @@
 org.gradle.parallel=true
 kotlin.code.style=official
 
-#compose.version=0.1.0-m1-build57
+# A version of Compose libraries,
+# that will be used by published Gradle plugin,
+# unless overridden by COMPOSE_GRADLE_PLUGIN_COMPOSE_VERSION env var.
+#
+# __LATEST_COMPOSE_RELEASE_VERSION__
+compose.version=0.1.0-build113
+
+# A version of Gradle plugin, that will be published,
+# unless overridden by COMPOSE_GRADLE_PLUGIN_VERSION env var.
+deploy.version=0.1.0-SNAPSHOT