deprecate some settings module settings and save_graph_xml function params

[gboeing]

• deprecate settings module's default_accept_language, default_referer, default_user_agent, memory, nominatim_endpoint, overpass_endpoint, and timeout settings (renamed for v2.0.0 release in rename settings module's default_accept_language, default_referer, and default_user_agent #1129 and Rename settings memory, timeout, nominatim_endpoint, overpass_endpoint #1136)
• deprecate settings module's osm_xml_node_attrs, osm_xml_node_tags, osm_xml_way_attrs, and osm_xml_way_tags settings (removed for v2.0.0 release in Improve OSM XML file saving #1135)
• deprecate save_graph_xml function's node_tags, node_attrs, edge_tags, edge_attrs, edge_tag_aggs, merge_edges, oneway, api_version, and precision parameters (removed for v2.0.0 release in Improve OSM XML file saving #1135)

See also #1106