feat: Simplified bootstrap with crypto identity extension

[krille-chan]

closes https://github.com/famedly/product-management/issues/3493

I think it makes sense to still keep the Bootstrap class but offer a simplified API on top of it. The Bootstrap object with it's state makes sure that we do never run into a broken state (in theory) and some consumers might still want to use it.

[codecov]

Codecov Report

❌ Patch coverage is 75.29412% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.80%. Comparing base (7fd01a9) to head (c5e96b9).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/encryption/utils/crypto_setup_extension.dart	75.29%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2214      +/-   ##
==========================================
+ Coverage   57.67%   57.80%   +0.13%     
==========================================
  Files         157      158       +1     
  Lines       19592    19677      +85     
==========================================
+ Hits        11299    11375      +76     
- Misses       8293     8302       +9     

Files with missing lines	Coverage Δ
lib/encryption/utils/crypto_setup_extension.dart	75.29% <75.29%> (ø)

... and 2 files with indirect coverage changes

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[td-famedly]

apart from that lgtm!