Recent Commits to bindiff:main

Refactor `FlowGraph` and `CallGraph` creation to use factory methods

- Replace the constructors of `FlowGraph` with static factory methods (`Create` and `FromProto`) that return `absl::StatusOr`
- Update `CallGraph::AttachFlowGraph` and `DetachFlowGraph` to return `absl::Status` instead of throwing exceptions. Update call sites and tests to handle the new status-returning APIs.
- Same exercise for the IDA Pro plugin's `SetupTemporaryFlowGraphs()`

PiperOrigin-RevId: 958989365
Change-Id: Ic720e6452f20dcdd074abe26f5238dfe6ee5fe2a

Automated Code Change

PiperOrigin-RevId: 958953771
Change-Id: Ib9e8c2786d29ed92b08089a06c49a3893150c75f

#Cleanup headers, modernize to C++20

Cleanups in the BinDiff codebase:
- Include what you use
- Replaces `ABSL_CONST_INIT` with standard C++20 `constinit`.
- C++20 defaulted `operator==()`
- Removes deprecated GetName() and GetConfidence() methods in MatchFlowGraph, updating callers to use name() and confidence().
- Cleans up unused and missing header includes in BUILD, main_portable.cc, and match/flow_graph.h.
- Mark throwing methods in SQLite support code as deprecated

PiperOrigin-RevId: 958902120
Change-Id: I66db8e4e463da7c54d608037c3ba0777011a3eaa