The main goal of this PR is to safeguard when a base or instantiated scene changes (nodes renamed, moved or readded),
that the hierarchy is still maintained and the node and its overridden properties can be preserved.
What it does:
* Implements unique node IDs.
* These IDs act as a fallback to names when saving.
* The IDs are **USED AS A FALLBACK**, so they are just an addition. It should not break any current existing scene.
* If a scene renames or moves a node, inherited or instantiated scenes will no longer lose reference to it.
Unlike the previous approach, this one is intended to be a fallback, only used if the node is not found.
This makes it safer to implement and ensure that, at worst case, we fail to find the node, but nothing breaks.
Ensures all resource types support UIDs in a project.
This is required to fix:
* Scripts and many other resource types can't be referenced by UID and when refactored the references are lost.
* Path export properties can't use UID for unsupported types.
* Refactoring problems when files are moved outside the editor (this PR effectively fixes it).
* Editor properly refreshing paths if they changed externally while opened (as example, git update).
This needs to be addressed in a subsequent PR, but this one effectively sets the prerequisites.
Resource types that do not support UID will get a .uid file appended to them (this includes .gd, .gdshader, .gdextension, etc. files).
- Unify documentation, hoping to clear misconcepctions about about propagation of the cache mode across dependant loads.
- Clarify in docs that `CACHE_MODE_REPLACE` now also works on the main resource (from #87008).
- Add two recursive modes, counterparts of `CACHE_MODE_REPLACE` and `CACHE_MODE_IGNORE`, since it seems some need them (see #59669, #82830).
- Let resources, even loaded with one of the ignore-cache modes, get a path, which is useful for tools.
This improves the error message in our text resource parsing code to
help the user potentially fix parsing issues in case of failure. It also
helps with the debugging process of finding out which sub_resource is
causing the parser to fail with line messages.
This allows to include script_instance.h directly in the
generated gdvirtual.gen.inc, and remove excessive includes
from the codebase.
This should also allow Resource to use GDVIRTUAL macros,
which wasn't possible previously due to a circular dependency.
When saving resources, marking of already seen resources was
done too late, causing infinite loop traversing referenced resources
and eventual stack overflow. The change marks traversed resource
before descending to it's children, thus when this resource is
encountered again, it is already marked as seen and traversal stops.
