feat(feature-activation): add signal bits field

[glevco]

Acceptance Criteria

• Add signal_bits field to Transaction

Security Checklist

• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.

[codecov]

Codecov Report

Merging #428 (0cb568f) into master (a3a71a4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #428   +/-   ##
=======================================
  Coverage   95.60%   95.60%           
=======================================
  Files          40       40           
  Lines        2458     2458           
  Branches      278      278           
=======================================
  Hits         2350     2350           
  Misses        108      108           

Impacted Files	Coverage Δ
events/nftCreationTx.ts	100.00% <ø> (ø)
src/types.ts	98.65% <ø> (ø)