Store supply as Int bytes rather than string bytes

[sahith-narahari]

Description

follow up: #8798 (comment)

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #9051 (c26794f) into master (5247a55) will increase coverage by 0.00%.
The diff coverage is 53.84%.

❗ Current head c26794f differs from pull request most recent head 13e8cc2. Consider uploading reports for the commit 13e8cc2 to get more accurate results

@@           Coverage Diff           @@
##           master    #9051   +/-   ##
=======================================
  Coverage   58.99%   58.99%           
=======================================
  Files         575      575           
  Lines       32192    32203   +11     
=======================================
+ Hits        18992    18999    +7     
- Misses      10984    10986    +2     
- Partials     2216     2218    +2     

Impacted Files	Coverage Δ
x/bank/keeper/keeper.go	76.28% <50.00%> (-0.44%)	⬇️
x/bank/legacy/v043/store.go	84.61% <100.00%> (ø)
x/staking/simulation/operations.go	73.16% <0.00%> (-0.30%)	⬇️
x/staking/types/msg.go	55.55% <0.00%> (+0.62%)	⬆️

[jgimeno]

Good one, thanks Sahith!

[amaury1093]

lgtm, thanks. Could you update the SPEC 01_state.md too?

[fedekunze]

ACK pending changelog entry