dkg: replace hex with base64 for definition_hash

[dB2510]

Replace hex string to base64 string for definition_hash in dkg logs.

category: refactor
ticket: #753

[codecov]

Codecov Report

Merging #756 (975dd2b) into main (3836392) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #756      +/-   ##
==========================================
- Coverage   54.20%   54.17%   -0.03%     
==========================================
  Files         107      107              
  Lines       10476    10476              
==========================================
- Hits         5678     5675       -3     
- Misses       3971     3972       +1     
- Partials      827      829       +2     

Impacted Files	Coverage Δ
dkg/dkg.go	52.90% <100.00%> (ø)
app/app.go	57.75% <0.00%> (-0.75%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3836392...975dd2b. Read the comment docs.