Create distinct conflict option IDs for our current tree conflict resolution options (there are only 2 options which actually resolve a tree conflict).
The new options are only used in libsvn_client and 'svn' for now. The current libsvn_wc interfaces still force us to map conflict option IDs to svn_wc_conflict_choice_t. As a side effect, --accept mine-conflict still works with these tree conflicts, but that may change later (we'll need a different system than a single --accept option to resolve arbitrary tree conflicts in a non-interactive way).
* subversion/include/svn_client.h (svn_client_conflict_option_update_move_destination, svn_client_conflict_option_update_any_moved_away_children): Declare. (svn_client_conflict_option_id_to_wc_conflict_choice): Declare. This is a temorary interface which maps option ID to legacy conflict choice.
* subversion/libsvn_client/resolved.c (conflict_option_id_to_wc_conflict_choice): Rename to ... (svn_client_conflict_option_id_to_wc_conflict_choice): ... this and expose as a temporary public API function. Map the new option IDs to the legacy conflict choice 'mine-conflict' so libsvn_wc will still resolve these conflicts correctly. (resolve_conflict): Update caller. (svn_client_conflict_tree_get_resolution_options): Assign the new option IDs to their respective tree conflict options.
* subversion/svn/conflict-callbacks.c (builtin_resolver_options): Add new options IDs. Use code "u" for them, a mnemonic for "update", instead of "mc" ("mine-conflict"). (conflict_option_id_to_wc_conflict_choice): Remove. This was a copy of the same function in libsvn_client. (mark_conflict_resolved): Use the new svn_client_conflict_option_id_to_wc_conflict_choice() interface.