Refactor cpp and rust(rapier) code

[Ughuuu]

Split the main rust code into smaller logical groups.
Split the cpp code and group it into folders.

Rust code now:

Add support for double precision builds in rust code:

Also add to SConstruct a define REAL_T_IS_FLOAT to be used in the rapier wrapper to know what type to use as real.

Also remove the global variables used in space:

uint32_t g_query_collision_layer_mask = 0;
ObjectID g_query_canvas_instance_id;
rapier2d::Handle *g_query_exclude = nullptr;
uint32_t g_query_exclude_size = 0;
RID *g_query_exclude_body = nullptr;

and

RapierSpace2D *g_contact_events_space = nullptr;
RapierBody2D *g_contact_events_body1 = nullptr;
RapierBody2D *g_contact_events_body2 = nullptr;
uint32_t g_contact_events_shape1 = 0;
uint32_t g_contact_events_shape2 = 0;

And instead send them to the rapier code and then have the rapier code send them back.