LibIMAP: Add useful dbgln_if() printouts to IMAP::Parser

I couldn't run the parser in a debugger like I normally would, so I
added printouts to understand where the parser is failing.
More could be added, but these are enough to get a good idea of what
the parser is doing. It's very spammy, though, so enable it by flicking
the IMAP_PARSER_DEBUG switch :^)

Meta/CMake/all_the_debug_macros.cmake

@@ -73,6 +73,7 @@ set(ICMP_DEBUG ON)
 set(ICO_DEBUG ON)
 set(IMAGE_DECODER_DEBUG ON)
 set(IMAGE_LOADER_DEBUG ON)
+set(IMAP_PARSER_DEBUG ON)
 set(INTEL_GRAPHICS_DEBUG ON)
 set(INTEL_HDA_DEBUG ON)
 set(INTERRUPT_DEBUG ON)