Support AllowReserved in Path Implementation

[lmazuel]

No description provided.

[msyyc]

Python depends on urllib3,

• urllib3 will encode all the invalid characters by default: https://github.com/urllib3/urllib3/blob/da106d802a21f74f65248b7edd016705b48322f5/src/urllib3/util/url.py#L442-L448
• valid characters for path is _PATH_CHARS = set("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._-~") | set("!$&'()*+,;=") | set(":") | set("@", "/") (source code)
• valid characters for query is _QUERY_CHARS = _PATH_CHARS | set("?") (source code)
• urllib3 will try to avoid encode pre-encoded characters: https://github.com/urllib3/urllib3/blob/da106d802a21f74f65248b7edd016705b48322f5/src/urllib3/util/url.py#L238-L243

[tadelesh]

see: Encoding for path and query.loop