[BOLT] Support POSSIBLE_PIC_FIXED_BRANCH
Detect and support fixed PIC indirect jumps of the following form:
```
movslq En(%rip), %r1
leaq PIC_JUMP_TABLE(%rip), %r2
addq %r2, %r1
jmpq *%r1
```
with PIC_JUMP_TABLE that looks like following:
```
JT: ----------
E1:| L1 - JT |
|----------|
E2:| L2 - JT |
|----------|
| |
......
En:| Ln - JT |
----------
```
The code could be produced by compilers, see
https://github.com/llvm/llvm-project/issues/91648.
Test Plan: updated jump-table-fixed-ref-pic.test
Reviewers: maksfb, ayermolo, dcci, rafaelauler
Reviewed By: rafaelauler
Pull Request: https://github.com/llvm/llvm-project/pull/91667
