[llvm] [llvm-mca] Abort on parse error without -skip-unsupported-instructions (PR #90474)

[Peter Waller via llvm-commits]

peterwaller-arm wrote:

Implemented as proposed, PTAL.

* Also added a table to the PR body which shows the test coverage.
* Also added a release note and updated the command guide.

https://github.com/llvm/llvm-project/pull/90474