feat(scheduler.lua): add require function to load scripts at runtime (Lazy Loading)

[0xWaleed]

This require function will load scripts at runtime, it works like lua's original require function that is being disable by CFX
for security reasons. this will use CFX natives to load scripts instead of adding them to client_script or server_script entries.
Also this will help to do lazy loading scripts on demand.

usage: will be the same as lua require function. we don't use / for directory separator not the .lua extension to make it same as lua on other platforms.

require('resource-name.dir.dir.script') 

As per the cfx documentation with client side, you need to add the file to file entry in fxmanifest in order to load it at runtime.

Thank you blattersturm for your points for my previous PR, I changed what you mentioned in order to meet the requirements.
feel free to add changes that I need to work on.

#735

[blattersturm]

again?