strictRequired should allow properties from parent schemas

[JacobLey]

What issue does this pull request resolve? https://github.com/ajv-validator/ajv/issues/1950

What changes did you make?

• Extra tests to prove behavior
• Tweak keyword execution order to ensure properties -> subschema
• Clone it context when passing to subschema

Is there anything that requires more attention while reviewing? I'm assuming tests should already be covering important cases, and those all pass.

But I guess there could be some concern about maintaining order of keyword validations?

https://ajv.js.org/guide/modifying-data.html

the order of evaluation of keywords, while consistent between validations and not dependent on how schema object is created, is neither documented nor guaranteed

Although even if order did "break" something that appears to within the semver "contract" of AJV?