301/302 Redirects, FormData files, Cookies, Token authentication

Despite multiple new features, the overall API itself didn't change much. I believe theese changes, if it comes to that, should be released as 4.x.0 and not 5.0.0.

⭐ Added:

Token authentication class, works the same way as Bearer, but with "Token ..." prefix
Added MOVED_PERMANENTLY_301 and FOUND_302 Status objects
Headers got new methods: get_directive() and get_parameter(), add and set
Request.cookies for retrieving and cookies parameter for setting in all Response-like classes
Added docs and example for cookies usage
Added request.form_data.files that uses new Files and File classes for representing files uploaded using multipart/form-data

🪛Fixes:

Added tuple as possible Route.methods parameter type, changed typing from Union to Iterator
EDIT2: Fixed #68 and fixed #69

🛠️ Updated/Changed:

Redirect got new preserve_method parameter, which allows it to switch between 301, 302, 307 and 308
Redirect got new status parameter, which allow for manual status code setting
Updated docs and example for Redirect
Debug message after sending response now contains elapsed time of request processing e.g. 192.168.0.103 -- "GET /index.html" 242 -- "200 OK" 154 -- 182ms
Updated docs for FormData
Fixed typing for QueryParams, FormData and Headers, especially in get() and get_list()
EDIT1: Server.serve_forever now accepts poll_interval parameter which adds delay between calling .poll()
EDIT2: Changes in FormData.__init__() for edge cases, e.g. when there is no Content-Type header in POST request
EDIT3: Request.json() can now be accessed in PUT, PATCH and DELETE requests

🏗️ Refactor:

Moved _IFieldStorage to interfaces.py, also added _IXSSSafeFieldStorage version of interface that enables encoding HTML entities
Both QueryParams and FormData implement _IXSSSafeFieldStorage
Headers now implements _IFieldStorage and does not store original case of header names, functionally it is the same
Redone parsing multipart/form-data form data
Simplified parsing of request header bytes

I hope I included everything.

adafruit / Adafruit_CircuitPython_HTTPServer

301/302 Redirects, FormData files, Cookies, Token authentication #67