Add LocalVector move semantics (constructor and operator=).

[Ivorforce]

We've recently begun to introduce move semantics to core, for its performance benefits. Examples of functions that can benefit a lot from move semantics include SWAP (#100367), reduce_at and insert (#100477), and simple data transfer. For more information on motivation, see #100426.

For LocalVector, this is especially important because a copy-constructor and copy-assignment is forced to copy the entire array, and all elements in it.

Examples

This time I've gathered relevant beneficiaries through a [[deprecated]] trick. Here are some examples:

godot/modules/navigation/3d/nav_mesh_queries_3d.cpp

Lines 923 to 929 in 6395450

	LocalVector<uint32_t> simplified_path_indices;
	simplified_path_indices.reserve(p_path.size());
	simplified_path_indices.push_back(0);
	simplify_path_segment(0, p_path.size() - 1, p_path, squared_epsilon, simplified_path_indices);
	simplified_path_indices.push_back(p_path.size() - 1);
	return simplified_path_indices;

(the memory no longer has to be re-allocated to return the vector)

The same was happening in ShaderPreprocessor::advance:

godot/servers/rendering/shader_preprocessor.cpp

Line 122 in 6395450

return tokens;

SWAP calls also required double reallocations in e.g. OAHashMap on insert:

godot/core/templates/oa_hash_map.h

Lines 133 to 135 in 6395450

	SWAP(hash, hashes[pos]);
	SWAP(key, keys[pos]);
	SWAP(value, values[pos]);

e.g .from ShaderGLES3::Version::Specialization items:

godot/drivers/gles3/shader_gles3.h

Lines 95 to 100 in 6395450

	struct Specialization {
	GLuint id;
	GLuint vert_id;
	GLuint frag_id;
	LocalVector<GLint> uniform_location;
	LocalVector<GLint> texture_uniform_locations;

There's some more examples but I think that should be enough evidence that the addition is warranted :)

[hpvb]

LGTM, and part of the core types we want to have this property.

[Repiteo]

Thanks!