[lldb-dap] Deduplicate watchpoints starting at the same address on...

[lldb-dap] Deduplicate watchpoints starting at the same address on SetDataBreakpointsRequest. (#83192)

If a SetDataBreakpointsRequest contains a list data breakpoints which
have duplicate starting addresses, the current behaviour is returning
`{verified: true}` to both watchpoints with duplicated starting
addresses. This confuses the client and what actually happens in lldb is
the second one overwrite the first one.

This fixes it by letting the last watchpoint at given address have
`{verified: true}` and all previous watchpoints at the same address
should have `{verfied: false}` at response.