Port the build to Gradle

Closes gh-19609
Closes gh-19608

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/build.gradle

@@ -0,0 +1,16 @@
+plugins {
+	id 'java-library'
+	id 'org.springframework.boot.conventions'
+	id 'org.springframework.boot.deployed'
+}
+
+description = 'Spring Boot AutoConfigure Annotation Processor'
+
+dependencies {
+	testImplementation enforcedPlatform(project(':spring-boot-project:spring-boot-dependencies'))
+	testImplementation project(':spring-boot-project:spring-boot-tools:spring-boot-test-support')
+	testImplementation 'org.assertj:assertj-core'
+	testImplementation 'org.springframework:spring-core'
+	testImplementation 'org.junit.jupiter:junit-jupiter'
+
+}