Explicit path expansion iterator

[ivmarkov]

As much as I love Iterator monadic comprehensions (flat_map and friends), the IM path expansion logic in node.rs - which was using those - was resulting in huge iterators w.r.t. memory.

The rewrite of the path expansion logic in node.rs to use an explicit PathExpander iterator with mutable state saves ~ 5K RAM.
While more risky, the mutable logic is covered with unit tests.

Net-net I don't think this change would increase the codebase size, because while PathExpander is more verbose - methods from endpoint.rs and cluster.rs got retired, as these are no longer necessary with the explicit PathExpander.

[semanticdiff-com]

Review changes with SemanticDiff.

Analyzed 5 of 5 files.

Overall, the semantic diff is 8% smaller than the GitHub diff.

	Filename	Status
✔️	rs-matter/src/interaction_model/core.rs	0.87% smaller
✔️	rs-matter/src/data_model/core.rs	78.46% smaller
✔️	rs-matter/src/data_model/objects/cluster.rs	Analyzed
✔️	rs-matter/src/data_model/objects/endpoint.rs	0.47% smaller
✔️	rs-matter/src/data_model/objects/node.rs	7.49% smaller