support const generic

[katat]

This is to implement #142

Changes

AST:

• Generic is to represent the generic parameter in the function signature. This involves modifications to the AST parser to support the generic parameter syntax.

• GenericArray is to represent the Array type with symbolic size.

• Support default repeated array declaration.

TAST:

• Some minor updates to bypass the type-checking rules when comparing the types involve generic parameters.

MAST:

• A new compiler pipeline phase in the middle between TAST and circuit writer.
• Mainly responsible for inferring the generic parameters and type-checking the inferred types.

Circuit writer:

• Updated to replace TAST dependency with MAST.

todo

• [ ] add tests to cover more checking in mast.

• cover the different types of inferring and expected errors.

• cover the builtins with return type of generic array

• [ ] refine the function calls to reflect the pipeline; related to https://github.com/zksecurity/noname/pull/147

• [ ] clean up code