Add option to select `+` or `%20` space encoding.

[ag-TJNII]

Currently the library encodes spaces as +:

[13] pry(main)> BasicUrl.new(host: 'foo', protocol: 'http', path: 'some spaced string').to_s
=> "http://foo/some+spaced+string"

This is coming from URI.encode_www_form_component:

• https://github.com/TJNII/basic_url/blob/main/lib/basic_url.rb#L173
• https://ruby-doc.org/stdlib-3.1.0/libdoc/uri/rdoc/URI.html#method-c-encode_www_form_component

However, the server might not like + instead of %20. This encoding should be an option.