[PlayStation] Detect if an SBI file isn't present for a title which requires it and display a warning.

Wordy title is wordy.

There's around 200+ PAL/European titles that require SBI files to exist in order for the game to run properly.
Without it games will hang and you won't be able to play such titles.

Easy test case is with Crash Team Racing (Europe). Start the game and go into Adventure Mode.
Select whatever character and drive into Crash Cove (directly in-front of you), the game will freeze up after entering that level (in a Loading sequence).

Obviously BizHawk is able to detect the SBI file, cause when it exists the level is able to be loaded.
So that isn't a problem.

This is for the case for the people that have forgotten about this important file to prompt it going "Hey, you're missing the SBI file the game will not run without it."

I say "display a warning", and not "prompt a failure and refuse to boot", as there are patches that exist that allow the SBI file to be patched into the bin and be able to execute without said issues.

Start with the PlayStation SBI detection path and reproduce the Crash Team Racing (Europe) case by entering Adventure Mode and loading Crash Cove without its SBI file. Done means a warning appears when a required SBI file is missing, while allowing patched titles that do not require the file to boot.