feat: support for Latvian eID Eparaksts

[OskarsPakers]

This change is the implementation of Latvian electronic ID provider eParaksts. It features two authentication methods and two identity providers (implemented in a single file) eparaksts - authentication with ID card and card reader, eparaksts-mobile - with eParaksts mobile app
Eparaksts developer documentation here.
I have read, but not following commit prefixes, let me know if this is a showstopper.
I haven`t created a design document as this seems like a straightforward implementation.

Fixes #3859

Configuration needed for this identity provider:
scope: "urn:lvrtc:fpeil:aa"
issuerURL: "https://eidas.eparaksts.lv"

Let us know whan needs to be added./changed/

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
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  security@ory.sh) 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.

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1 out of 2 committers have signed the CLA.

✅ OskarsPakers
❌ martinsc

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[codecov]

Codecov Report

Attention: Patch coverage is 77.21519% with 18 lines in your changes are missing coverage. Please review.

Project coverage is 78.05%. Comparing base (5288bc7) to head (139ad5e).
Report is 1 commits behind head on master.

❗ Current head 139ad5e differs from pull request most recent head 812e6cc. Consider uploading reports for the commit 812e6cc to get more accurate results

Files	Patch %	Lines
selfservice/strategy/oidc/provider_eparaksts.go	77.21%	11 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3826      +/-   ##
==========================================
+ Coverage   78.02%   78.05%   +0.03%     
==========================================
  Files         362      361       -1     
  Lines       25296    25355      +59     
==========================================
+ Hits        19737    19791      +54     
+ Misses       4047     4046       -1     
- Partials     1512     1518       +6     

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