[clang][Tooling] Fix addTargetAndModeForProgramName to use correct flag names

The logic was using incorrect flag versions. For example:
- `-target=` can't be a prefix, it must be `--target=`.
- `--driver-mode` can't appear on its own, value must be attached to it.

While fixing those, also changes the append logic to make use of new
`--target=X` format instead of the legacy `-target X` version.

In addition to that makes use of the OPTTable instead of hardcoded strings to
make sure helper also gets updated if clang's options are modified.

Differential Revision: https://reviews.llvm.org/D85076