feat: selfservice/admin session management

[zepatrik]

Related issue(s)

closes #655
closes #2007

Checklist

• I have read the contributing guidelines.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I am following the
  contributing code guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security. vulnerability, I
  confirm that I got green light (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further Comments

[codecov]

Codecov Report

Merging #2011 (117dd35) into master (4a3e2df) will decrease coverage by 0.01%.
The diff coverage is 82.49%.

❗ Current head 117dd35 differs from pull request most recent head 8edbde1. Consider uploading reports for the commit 8edbde1 to get more accurate results

@@            Coverage Diff             @@
##           master    #2011      +/-   ##
==========================================
- Coverage   75.04%   75.03%   -0.02%     
==========================================
  Files         293      293              
  Lines       15374    15568     +194     
==========================================
+ Hits        11538    11681     +143     
- Misses       3008     3047      +39     
- Partials      828      840      +12     

Impacted Files	Coverage Δ
identity/handler.go	86.27% <ø> (ø)
schema/handler.go	82.53% <ø> (ø)
session/persistence.go	0.00% <ø> (ø)
x/pagination.go	100.00% <ø> (ø)
session/handler.go	70.06% <54.54%> (-18.25%)	⬇️
persistence/sql/persister_session.go	80.70% <77.27%> (-2.16%)	⬇️
session/test/persistence.go	100.00% <100.00%> (ø)
selfservice/flow/registration/handler.go	70.68% <0.00%> (-6.17%)	⬇️
identity/identity_verification.go	65.00% <0.00%> (-3.97%)	⬇️
courier/courier.go	69.44% <0.00%> (-3.48%)	⬇️
... and 12 more

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[aeneasr]

I changed the URL structure a bit to conform the rest of the codebase better. Otherwise, this is good to merge but should get a bit of docs :)

[aeneasr]

pop v6 😅