[BOLT][NFC] Add aliases for ICP flags

- `indirect-call-promotion` -> `icp`
- `indirect-call-promotion-mispredict-threshold` -> `icp-mp-threshold`
- `indirect-call-promotion-use-mispredicts` -> `icp-use-mp`
- `indirect-call-promotion-topn` -> `icp-topn`
- `indirect-call-promotion-calls-topn` -> `icp-calls-topn`
- `indirect-call-promotion-jump-tables-topn` -> `icp-jt-topn`
- `icp-jump-table-targets` -> `icp-jt-targets`

This also fixes an inconsistency in ICP flag names that some start with
`indirect-call-promotion` while others start with `icp`.

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D128375