GitLab

Fixes #3222, fixes #3225, closes #3223

PiperOrigin-RevId: 352066131

Add "using is_gtest_matcher = void" to the DivisibleBy7Matcher example.

PiperOrigin-RevId: 351797821

Change Matcher<T> to allow binding an implementation by value directly:
 - Drop the requirement of MatcherInterface. Doing manual type erasure avoid
   extra layers in many cases.
 - Avoid the adaptor for `MatcherInterface<T>` and `MatcherInterface<const T&>` mismatch.
 - Use a small object optimization when possible. This makes things like
   `_` and `Eq(1)` really cheap and do not require memory allocations.
 - Migrate some matchers to the new model to speed them up and to test the new framework. More matchers to come in future changes.

PiperOrigin-RevId: 350580998

Move all docs into top-level docs/ directory

PiperOrigin-RevId: 350211277