Detection of template haskell can be more precise

**Shared Program**: https://code.world/haskell#PvmcFl0m1uGPxR-OH8_lVeQ

**Description**

The detection of template-haskell currently just looks for any of "TemplateHaskell", "QuasiQuote" or "glasgow-exts" as a substring of the source file. This isn't saying exactly what we want. In particular:

1. This might not be sufficient in the future to detect all ways to turn on TemplateHaskell. GHC could add new flag sets that have this effect (in the same way that -fglasgow-exts does now).

2. These strings can sometimes occur in comments, string literals, etc., where they are innocent, but the program is rejected anyway.

Copied from a comment on #1072:

> codeworld-compiler now links ghc-lib-parser, and parseDynamicFilePragma can be used to parse language and options pragmas from the source code into dflags, and then we can check for use of the language flags in the resulting DynFlags value. There's existing code for this in CodeWorld.Compile.Framework ghcParseCode.

@misterbeebee FYI

Empieza leyendo CodeWorld.Compile.Framework.ghcParseCode y la lógica actual de detección de Template Haskell. Usa parseDynamicFilePragma de ghc-lib-parser para inspeccionar las pragmas de language y options, y luego verifica que la detección se base en los flags analizados en lugar de en subcadenas de comentarios o literales de cadena. Se considera terminado cuando se detectan todas las formas admitidas de habilitar Template Haskell sin rechazar apariciones inocuas.

Escrito por el modelo de indexación a partir del texto del issue.