Add asmparser/printer support for locations to make them round-trippable....

Add asmparser/printer support for locations to make them round-trippable. Location printing is currently behind a command line flag "mlir-print-debuginfo", we can rethink this when we have a pass for stripping debug info or when we have support for printer flags.

Example inline notation:

  trailing-location ::= 'loc' '(' location ')'

  // FileLineCol Location.
  %1 = "foo"() : () -> i1 loc("mysource.cc":10:8)

  // Name Location
  return loc("foo")

  // CallSite Location
  return loc(callsite("foo" at "mysource.cc":19:9))

  // Fused Location
  /// Without metadata
  func @inline_notation() loc(fused["foo", "mysource.cc":10:8])

  /// With metadata
  return loc(fused<"myPass">["foo", "foo2"])

  // Unknown location.
  return loc(unknown)

Locations are currently only printed with inline notation at the line of each instruction. Further work is needed to allow for reference notation, e.g:
     ...
     return loc 1
   }
   ...
   loc 1 = "source.cc":10:1

PiperOrigin-RevId: 230587621