Consider time in BuildInfo up-to-date checks and allow it to be set

Closes gh-12111
Closes gh-12266

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoIntegrationTests.gradle

@@ -16,5 +16,8 @@ task buildInfo(type: org.springframework.boot.gradle.tasks.buildinfo.BuildInfo)
 		group = property('buildInfoGroup', 'foo')
 		name = property('buildInfoName', 'foo')
 		additional = ['additional': property('buildInfoAdditional', 'foo')]
+		if (project.hasProperty('nullTime')) {
+			time = null
+		}
 	}
 }