Support prompt login

[jesseyay]

Hi team, thanks for the great library!

Description of the Change

Adds support for prompt=login to comply with https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[codecov]

Codecov Report

Merging #1164 (95935dc) into master (c22c179) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@ Coverage Diff @@## master #1164 +/- ## ========================================== + Coverage 96.87% 96.90% +0.03%  ========================================== Files 31 31 Lines 1794 1812 +18 ========================================== + Hits 1738 1756 +18  Misses 56 56 

Impacted Files	Coverage Δ
oauth2_provider/views/base.py	97.88% <100.00%> (+0.30%)	⬆️

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[n2ygk]

Hey thanks! Please see a couple of documentation suggestions.

[jesseyay]

Hey thanks! Please see a couple of documentation suggestions.

Yep makes sense, thanks for the review :)

[n2ygk]

darn it, I tried to rebase to fix the CHANGELOG conflict...