Make EE data const or zero-initialized for cleaner (re-)initialization

[uyjulian]

Some functions have added const arguments accordingly
Initialization has been moved inside functions, or ctors if there is no conveient function
Some global variables have been made local, static, or removed
Sema, Thread, DmacHandler, IntcHandler, and fd handle 0 as invalid

wLE tested working

[fjtrujy]

Hello @uyjulian ,
I don't have anything against this PR; however, there are many conditions that were changed from >= 0 to > 0 and the opposite in other scenarios from < 0 to <= 0, when creating semaphores, mutexes, threads, and similar.
Have you checked that all these return values were previously wrong?

[uyjulian]

The return value on error is -1, but those functions never return the value 0. I am using that property to initialize the variables, so I changed the conditions so that it can handle that case properly.