Seemingly-redundant error codes

[david-christiansen]

Presently, both [GHC-76037] (TcRnNotInScope) and [GHC-88464] (TcSolverReport (SolverReportWithCtxt { reportContent = ReportHoleError ...) give very similar string messages, but are distinct:

<interactive>:2:7: error: [GHC-88464]
    Data constructor not in scope: X
ghci> \X -> X

<interactive>:3:2: error: [GHC-76037]
    Not in scope: data constructor ‘X’

We should follow up with the GHC folks about whether these should have the same code.