feat(auth): add methods for updating and resetting password

[tdakkota]

Updates #615.

[codecov]

Codecov Report

Merging #682 (26c5138) into main (30f12fb) will increase coverage by 0.14%.
The diff coverage is 82.93%.

@@            Coverage Diff             @@
##             main     #682      +/-   ##
==========================================
+ Coverage   69.24%   69.39%   +0.14%     
==========================================
  Files         426      430       +4     
  Lines       20413    20526     +113     
==========================================
+ Hits        14135    14243     +108     
+ Misses       5373     5372       -1     
- Partials      905      911       +6     

Impacted Files	Coverage Δ
telegram/auth/signup.go	73.33% <ø> (ø)
telegram/auth/user.go	59.25% <50.00%> (+4.60%)	⬆️
internal/crypto/srp/new_hash.go	75.00% <75.00%> (ø)
telegram/auth/password.go	77.27% <77.27%> (ø)
internal/crypto/srp/hash.go	87.83% <87.83%> (ø)
internal/crypto/srp/pad.go	100.00% <100.00%> (ø)
internal/crypto/srp/srp.go	100.00% <100.00%> (+12.76%)	⬆️
internal/testutil/rand.go	72.72% <100.00%> (+2.72%)	⬆️
telegram/auth/flow.go	76.08% <100.00%> (+2.75%)	⬆️
telegram/updates/gap_buffer.go	71.42% <0.00%> (-10.72%)	⬇️
... and 8 more

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