ENH: consistent reporting and exit codes for pytensor-cache clear and unlock #2534

Description

Observed behavior across the mutating commands:

• clear prints nothing on success; it warns only when tmp* entries remain.
• unlock prints "Lock successfully removed!" even when no lock existed (verified: exit 0).
• clear and cleanup exit 0 even when delete_if_problem=True leaves files behind.

So some commands report their outcome and some do not, and the exit code does not distinguish full success from partial success.

Proposal

Make outcome reporting consistent across commands:

• Every command reports what it did in the same style: action taken, count/bytes where applicable.
• unlock: distinguish "no lock found" from "removed stale lock".
• Exit codes reflect the outcome: nonzero on partial failure.

Reporting goes to stderr per #2531; data summaries on stdout.