Watch known changing locations

[lptr]

This is a follow-up to #13887 and the second step towards #13598.

We can also watch certain things that we know might change and were used as inputs. Examples are:

• Maven, Ivy and flat dir local repositories
• system headers for native compilation

---

cc: @gradle/execution

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Given the limited bandwidth of the team, it will be automatically closed if no further activity occurs. If you're interested in how we try to keep the backlog in a healthy state, please read our blog post on how we refine our backlog. If you feel this is something you could contribute, please have a look at our Contributor Guide. Thank you for your contribution.