Rationalise handling of “current” build operation and build operation IDFor an upcoming change to emit console logging as build operation progress events, we need to associate all progress logging with the build operation. This pulled a thread on some long overdue cleanup.The end result is:1. Base build operation infrastructure is consolidated org.gradle.internal.operations.2. Mechanism for passing thread global current build operation is more test friendly, and better named.3. A consistent mechanism is used for binding the current operation to the thread, instead of two mechanisms.4. Build operation IDs are typed to OperationIdentifier.There is no public API or user behaviour change.