Convert type spec to Type.t

[yoshihiro503]

Implement all case of the function Type.of_absform.

• [x] Type annotations: TyAnn
• [x] Atoms: atom(), 'ok'
• [x] Singleton Integer: 1, and number()
• [x] any()
• [x] none()
• [x] boolean()
• [x] Tuples: TyTuple
• [x] Unions: TyUnion
• [x] pid() port() reference() identifier() #255
• [ ] non_neg_integer(), integer(), pos_integer(), neg_integer()
• [ ] float() byte() char()
• [ ] range: TyRange
• [ ] binary() bitstring() and Bitstring
• [x] Lists (proper and improper) #246
• [x] Strings (= list(char())) #246
• [ ] iodata() (= iolist() | binary()), iolist() (= maybe_improper_list(byte() | binary() | iolist(), binary() | []))
• [ ] function(), TyFun, TyFunAny
• [ ] TyFunAnyArity
• [x] TyContFun #247
• [ ] TyAnyTuple
• [ ] module() mfa() node()
• [ ] timeout()
• [ ] no_return()
• [ ] Binary and Unary Operators: TyBinOp, TyUnaryOP
• [x] Maps: TyAnyMap TyMap #246
• [ ] User defined type : TyUser
• [ ] TyLit
• [ ] Records: TyRecord
• [ ] Remote types: TyRemote