Support new type variable syntax

[KaanOzkan]

Motivation

Fixes: #901

Implementation

The implementation is best read commit by commit, but generally does the following:

1. Changes the signature and processing of arguments for the type_member and type_template method patches so that it supports bounds being supplied both as keyword arguments and as the result of calling the block.
2. Extracted the type variable serialization logic to a helper module, which does a Sorbet feature check to generate the correct type variable serialization (i.e. parameter based one for old Sorbet versions and block based one for new Sorbet versions)
3. Refactored the create_type_member RBI helper method to be a more generic and finer-grained create_type_variable helper method that expects all type variable parts (that is type, variance, fixed, upper and lower) and serializes it using the serialization helper mentioned in the previous step. This allows all DSL RBIs to properly serialize their type variable annotations.
4. Finally, bumped the Sorbet version and ported all Tapioca codebase to use the new type variable syntax.

Tests

• Updated existing tests to test the ability to read both the old and the new type variable syntax and to generate the new type variable syntax in RBI files. Since Tapioca depends on a recent Sorbet version for development now, we can test outputting old type variable syntax in these tests.
• Added new gem CLI tests to run against an old and a new Sorbet version to test both reading and writing the old and new syntax type variable syntax. These tests complete the coverage for this feature.

[paracycle]

Thank you, this is good start. In general, it would be great to have this working both ways, depending on the version of Sorbet this code is working against, so that we can backport this to the 0.7.x series and unblock users.

[Morriar]

Can we add a test showing the different behavior with an old Sorbet version? 🙏

[Morriar]

Amazing, thanks! ❤️