Add Get Context Help Image to improve lookup and avoid crashes

Picking up from my wild ramblings on this Zulip Chat Item where I was experiencing crashes when looking up the Icon and Context Help Image for an In-Place-Element Structure on a palette.

I automated some testing of which function-IDs caused crashes for LV 2020 and LV 2024 and it seems that IDs 343 and 344 are the only ones that cause crashes.

I noticed that the existing code tried to handle some bad IDs (335, 336) but I suspect these have changed since LV2014.

With this change I build a index of valid IDs on the first call of Get BuiltIn Function Name and Image.vi which can then be used to get the context images more easily on future calls.

I had some discussion with Darren Nattinger on the LabVIEW Discord and he suggested skipping IDs between 335-397 but some of these seem like they might be dropped onto custom palettes so I have chosen to be less conservative and only explicitly exclude the ones that crash labview. Others that just return an error won't be added to the index of valid Function IDs.

Let me know what you think and if you would like me to make any changes.

Thanks!