[BOLT] Use ULEB128 encoding for PIE/DSO exception tables (#116911)
Use ULEB128 encoding for call sites in PIE/DSO binaries. The encoding
reduces the size of the tables compared to sdata4 and is the default
format used by Clang.
Note that for fixed-address executables we still use absolute addressing
to cover cases where landing pads can reside in different function
fragments.
For testing, we rely on runtime EH tests.