🔥 Remove deprecated matcher

[phatblat]

Are we ready for this yet? Looks like v9 work has started in master and this might be a good time to drop the deprecated Matcher.

Tests still need some work; they compile but I still need to track down crashes.

The PR should summarize what was changed and why. Here are some questions to
help you if you're not sure:

• What behavior was changed?
• What code was refactored / updated to support this change?
• What issues are related to this PR? Or why was this change introduced?

Checklist - While not every PR needs it, new features should consider this list:

• Does this have tests? Mostly deleting/simplifying tests.
• Does this have documentation? Docs need to be updated
• Does this break the public API (Requires major version bump)? Yes 💥
• Is this a new feature (Requires minor version bump)? Yes 💥

[ikesyo]

Let's consider the deprecation roadmap in the README: https://github.com/Quick/Nimble/blob/master/README.md#deprecation-roadmap

• We need to do the following before removing the APIs

  • Introduce warnings on migration-path features (.predicate, Predicate-constructors with similar arguments to old API).

• The README change in #689 needs to be reverted

[ikesyo]

Submitted #746 for migration-path features deprecation.

[ikesyo]

Superseded by #746.