Consolidate parsing of `Expr::Name` in `TypeAliasName`, `MatchName`, and `Atom<Goal>`

[zanieb]

We have three parser descriptions for in the LALRPOP grammar for generating Expr::Name from an Identifier.

• TypeAliasName
• MatchName
• Atom<Goal>

These could be consolidated into a single reused identifier for simplicity and clarity.

Originally posted by @MichaReiser in #97 (comment)

[zanieb]

TypeAliasName may not be compatible with MatchName per #99