Validate query parameters and reject non-scalars

[clue]

This changeset ensures we properly validate any query parameters and reject unsupported non-scalars such as objects/arrays/resources. This should be in line with the existing design and should not affect any existing code using scalar or null values.

// old (still supported)
$mysql->query('SELECT * FROM user WHERE name = ? and age > ?', ['Alice', 42]);

// now throws an InvalidArgumentException for invalid params
$mysql->query('SELECT ?', [new stdClass()]);

Most notably, this fixes an old bug that would invalidate the entire connection object if an unexpected value is passed as discussed in #167. With these changes applied, it will now properly reject any invalid values, leaving the connection in a valid state for any following queries. The affected code comes with updated tests that have 100% code coverage.

Additionally, it adds some stricter types to the public API that makes it easier to detect this problem for any static analysis tools such as PHPStan or your favorite IDE.

On top of this, this is done in preparation for named query params as discussed in #41. Among others, this will change the list type to an array type again. I'll file a follow-up PR once this one is in.

If you want to support this project, please consider sponsoring @reactphp – sponsorships really do make a difference ❤️

Builds on top of #210, #186, #40, clue/reactphp-redis#171, and others
Resolves / closes #167
Refs #41

[PaulRotmann]

👍