Use `parse_url_opts` to simplify/remove `builder.rs`

[kylebarron]

In recent versions of object_store, parse_url and parse_url_opts were added. This looks like it should significantly simplify the code in builder.rs.

One drawback so far is that I can't tell how to pass ClientOptions, since that seems to be considered separately from the other options. (I.e. other options are passed to with_config while client options should be passed in to with_client_options)