Fix infinite recursion caused by circular asset references in Lottie files

A malicious Lottie JSON file with a self-referencing or mutually
referencing precomp asset (e.g. asset "a" containing a layer with
refId="a") caused infinite recursion in renderer::CompLayer::CompLayer()
via createLayerItem(), crashing the process with SIGSEGV.

Fix: in resolveLayerRefs(), build a directed asset dependency graph
and run BFS from each asset to detect cycles before assigning
mChildren. Any Precomp layer whose refId resolves to a cyclic asset
is skipped, leaving its mChildren empty and rendering nothing instead
of crashing.

Handles both direct self-reference (A → A) and indirect mutual
reference (A → B → A).