Make pretty-printed core more readable

[timsueberkrueb]

In #1181 we made the core pretty printer a lot more verbose in order to enable re-parsing. However, the additional verbosity hinders human inspection and debugging. This PR aims to mitigate this by splitting the core pretty printer in two instances:

• ReparsablePrettyPrinter is fully verbose and can be re-parsed with core.Parser
• HumanReadablePrettyPrinter is less verbose (and thus more readable) but cannot be re-parsed

[timsueberkrueb]

We can probably get rid of this by moving the userName logic to idFor. We need to be careful with this, though, as idFor is also used by core.Parser.

[marvinborner]

You may want to use --debug instead of --detailed-ir, as we do for more debug information in the LLVM IR.

[timsueberkrueb]

Also remove some of the captures currently printed by default. It would also be good to highlight get and put as keywords in the VSCode plugin.

[timsueberkrueb]

Corresponding VSCode extension PR: effekt-lang/effekt-vscode#163

[jiribenes]

Q from the meeting: does util.show(...) show the ID in addition to the string?

[timsueberkrueb]

I just checked: it always prints some ids:

• If --debug is not set, it prints the Barendregt ids actually used internally in the compiler
• If --debug is set, it runs in the reparsable mode (printDetailed, currently conflated with the debug mode) and prints a deterministic id starting from zero.

  def toDoc(s: symbols.Symbol): Doc = {
    // In human-readable mode, we show the name together with the actual Barendregt id.
    // This allows the user to connect the symbol to the internal representation when debugging.
    // In reparsable mode, we just show the string part, which should be freshened by the TestRenamer before printing.
    // The TestRenamer does not rename the Barendregt id because that would violate the internal invariant of having
    // just a single global Barendregt namespace.
    builtins.coreBuiltinSymbolToString(s).getOrElse(if printDetails then s.name.name else s.show)
  }

I can change this behavior to always print the internal Barendregt ids except when deterministic ids are needed for test cases.