feat(r8-tests): Add R8 source file tests

[romtsn]

Part of #40

Unsure if we actually have to handle such weird inputs, but I guess we better be on the safe side and parse those correctly.

R8 Retrace Test Coverage

• Inlining (13 tests) - inline frames, line numbers, source files, rewriteFrame rules
• Ambiguous Methods (21 tests) - multiple methods → same obfuscated name, alternatives
• Outlines (4 tests) - outline callsites, nested outlines, inline-in-outline
• Synthetic/Lambda (3 tests) - lambda methods, synthetic bridges
• Source File Edge Cases (7 tests) - colons, unicode, multiple dots, synthesized names
• Line Number Handling (10 tests) - spans, preambles, invalid ranges, missing lines
• Exception Handling (6 tests) - obfuscated exceptions, suppressed, circular refs
• Method Overloading (4 tests) - overloads with/without ranges
• Mapping Versions (2 tests) - version warnings, multiple versions
• Special Formats (4 tests) - Java 9+ modules, logcat format, auto-detect
• Identity/Passthrough (2 tests) - identity mappings
• Real-World Bot Tests (4 tests) - production stack traces
• Edge Cases (6 tests) - invalid input, dashes in names, whitespace, field overlap