Move setting of Save context flags from Patches to Savecontext

[GSKirox]

Another PR with the goal of cleaning Patches.py a tiny bit.
Instructions that write initial save context flags have been regrouped and divided in two functions moved in SaveContext.py :

• write_qol_save_context_flags, which are currently always on whatever the settings chosen. Since they don't use any other data, this can be a member of SaveContext.
• write_settings_dependent_save_context_flags for the rest, in a function separate of the class.

I chose to let a couple of these flags in Patches.py if they were part of a bigger code block for their specific settings, since i felt it would make it less readable if that flag was set somewhere else.

This should be strictly indentical in behaviour, barring of course any mistake.