Add ELF symbol binding to JSON dump

- Remove unused ConvertElfFunctionIR and ConvertElfObjectIR.
- Convert ELF symbol binding from IR to JSON in AddElfSymbolMessageIR.

Bug: 112877706
Test: ./test.py
Change-Id: Ib07b19f76dbbebe751583a3fb95eabe7e2ac7e40
8 files changed