Deduplicate call-DAG traversals and cache nullptr in InferType

[rjodinchr]

Several passes traversed call graphs or argument user chains without marking nodes as visited when enqueuing, causing exponential O(2^D) traversal times and memory growth on deep diamond call DAGs:

• AutoPodArgsPass: insert into visited_fct when pushing to next_fcts_to_visit
• ShareModuleScopeVariables: return early if entry_point is already recorded
• CallGraphOrderedFunctions: deduplicate sorted callees list
• SpecializeImageTypes: track visited arguments in RemapUse
• AllocateDescriptorsPass: track visited arguments in HasReadsAndWrites
• Types: cache nullptr in InferType to avoid re-traversing call graphs for untyped pointer arguments

Ref #1668

[gemini-code-assist]

Code Review

This pull request introduces several optimizations and safety checks across various passes to prevent redundant processing and infinite recursion. Specifically, it adds visited-set checks in AllocateDescriptorsPass, AutoPodArgsPass, and SpecializeImageTypesPass, deduplicates callees in CallGraphOrderedFunctions, and optimizes entry point tracing in ShareModuleScopeVariablesPass. In Types.cpp, recursion guards and caching are introduced to InferType. However, a critical issue was identified where permanently caching nullptr in InferType can lead to incorrect type inference failures due to recursion guards. It is recommended to revert this change and return nullptr without caching it permanently.