feat: bidirectional refactor #1

[jackprogramsjp]

Plan / Implementation

• Refactor the codebase to also include a top-down approach to implement bidirectional. This allows for better type errors and nicer organization.
• Check against array literals. This PR can be extended more, but this will just be the starting point. More can be added. The point is to gradually refactor, rather than rewrite everything at once.

Some Tests have already passed without bidirectional.

Current Steps

• Check array literals against expected T[] for each element
• When a function has a declared return type, the return value should be checked against that type.

Test plan

• dotnet test should show all green
• Add any other possible tests that may pop up during implementation.

[jackprogramsjp]

Ready to get reviewed for merge.

Changes

1. More special cases are expected to be added later as well, but for now, array literals.
2. For a type annotated let, when there's initialization, goes through checking against declared type.
3. Return expression is also checked against return type when present.
4. Non-generic call arguments are checked.
5. Assignments are checked
6. Expression bodied functions checked
7. Interface properties and index initializers checked
8. Generic calls checked (explicit ::<T> and inferred)
9. Inference order
10. GetContextualType fix (has to read ColonTypeClause.Type, not clause.