[BOLT] Add tests for pre-aggregated parsing (#193843)
Extends e2e coverage of pre-aggregated profile parsing to match the
unit-test coverage added in #192390:
- R (Return) records, including the branch=0 fallback path that
rewrites to the FT_EXTERNAL_RETURN sentinel.
- r (FT_EXTERNAL_RETURN) records.
- B and T records using the negative -1 hex form (#192391),
which is parsed as the BR_ONLY/FT_ONLY sentinel.
- Error paths: invalid record type letter and malformed hex address
(perf2bolt is expected to exit non-zero with a parser error).
The two error-path inputs are tiny raw files under Inputs/ since they
contain intentionally malformed records that link_fdata doesn't process.
Test Plan:
added bolt/test/X86/pre-aggregated-records.s
