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

[michalpokusa]

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 Submitting empty form, or forms with only checkboxes, causes crash in web server #68 and fixed request.form_data.get(...) returns the string "None" if a field doesn't exist #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.

[FoamyGuy]

This looks good to me.

I tested as much of the new features and fixes as I could on a combination of Metro S3, and Feather S3 TFT both on 9.0.0 latest release from S3.

Thank you for all of the improvements!

[michalpokusa]

@FoamyGuy Thank you for testing and review, I believe the PR is now ready to be merged and released as 4.4.0.

Some time ago there was also an issue about a link in release, seems it was not closed with previous release #65