[dsymutil] Add -q/--quiet flag to suppress warnings (#91658)

Add a -q/--quiet flag to suppress dsymutil output. For now the flag is
limited to dsymutil, though there might be other places in the DWARF
linker that could be conditionalized by this flag.

The motivation is having a way to silence the "no debug symbols in
executable" warning. This is useful when we want to generate a dSYM for
a binary not containing debug symbols, but still want a dSYM that can be
indexed by spotlight.

rdar://127843467