[lldb] Add Function::GetAddress and redirect some uses (#115836)

Many calls to Function::GetAddressRange() were not interested in the
range itself. Instead they wanted to find the address of the function
(its entry point) or the base address for relocation of function-scoped
entities (technically, the two don't need to be the same, but there's
isn't good reason for them not to be). This PR creates a separate
function for retrieving this, and changes the existing
(non-controversial) uses to call that instead.

GitOrigin-RevId: 66a88f62cd56e55b5fa0ddb1bdffa549f7565f8f
22 files changed