Add Gradle precompiled script plugin sample

See https://docs.gradle.org/current/userguide/custom_plugins.html#sec:precompiled_plugins

Signed-off-by: Vladimir Sitnikov <sitnikov.vladimir@gmail.com>

sandbox/README.md

@@ -13,3 +13,7 @@
 
   Try running `./gradlew :gradle-sign-file:signFile`.
   The output will be put into `gradle-sign-file/build/sigstore/signFile`
+
+* [Precompiled plugin](gradle-precompiled-plugin)
+  Shows the way `dev.sigstore.sign` can be a part of a
+  [precompiled script plugin](https://docs.gradle.org/current/userguide/custom_plugins.html#sec:precompiled_plugins).

sandbox/gradle-precompiled-plugin/build.gradle.kts

@@ -0,0 +1,14 @@
+plugins {
+    `kotlin-dsl`
+}
+
+repositories {
+    gradlePluginPortal()
+}
+
+dependencies {
+    // dev.sigstore.sign:dev.sigsore.sign.gradle.plugin is preferable,
+    // however Gradle does not recognize .gradle.plugin within included build,
+    // so we use the fallback
+    implementation("dev.sigstore:sigstore-gradle-sign-plugin")
+}

sandbox/gradle-precompiled-plugin/src/main/kotlin/sigstore-conventions.gradle.kts

@@ -0,0 +1,9 @@
+plugins {
+    id("dev.sigstore.sign")
+}
+
+sigstoreSign {
+    oidcClient {
+        gitHub()
+    }
+}

sandbox/settings.gradle.kts

@@ -2,6 +2,7 @@ rootProject.name = "sigstore-sandbox"
 
 include("gradle-sign-file")
 include("gradle-sign-java-library")
+include("gradle-precompiled-plugin")
 
 // Include dev.sigstore.sign plugin
 includeBuild("../")

sigstore-gradle/sigstore-gradle-sign-plugin/build.gradle.kts

@@ -6,7 +6,7 @@ plugins {
 description = "Gradle plugin to that automatically signs all Publications in Sigstore"
 
 dependencies {
-    implementation(project(":sigstore-gradle:sigstore-gradle-sign-base-plugin"))
+    api(project(":sigstore-gradle:sigstore-gradle-sign-base-plugin"))
 
     testImplementation(project(":sigstore-testkit"))
 }