@defichain/testing createToken to return id number

[fuxingloh]

What kind of PR is this?:

/kind feature

What this PR does / why we need it:

Testing module token.createToken to return number id of the created token for testing QOL.

[github-actions]

size-limit report 📦

Path	Size	Loading time (3g)	Running time (snapdragon)	Total time
packages/jellyfish/dist/jellyfish.umd.js	18.93 KB (0%)	379 ms (0%)	150 ms (-10.67% 🔽)	528 ms

[codecov]

Codecov Report

Merging #234 (896fcb7) into main (dc80d46) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #234   +/-   ##
=======================================
  Coverage   96.22%   96.22%           
=======================================
  Files          66       66           
  Lines        1696     1697    +1     
  Branches      234      234           
=======================================
+ Hits         1632     1633    +1     
  Misses         64       64           

Impacted Files	Coverage Δ
packages/testing/src/token.ts	100.00% <100.00%> (ø)

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