fix: better handle token registration errors

[sebastiendan]

Description

This PR fixes the token registration error handling.

The problem was that without an explicit gasLimit, the token registration transaction would fail without clear error in case of for instance insufficient funds. This came from the lack of explicit gasLimit in that transaction sending (gas estimation isn't working well with custom params).

The PR also introduces a design change: the top-context setErrors helper function is now called in the component rather than the hook. This may be replicated to all other hooks in the future, as the presentation layer should cover the error display.

Fixes TOO-410

PR Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added or updated tests that comprehensively prove my change is effective or that my feature works

[codecov]

Codecov Report

Attention: 15 lines in your changes are missing coverage. Please review.

Comparison is base (6308e74) 87.64% compared to head (2825505) 88.04%.

Files	Patch %	Lines
packages/frontend/src/components/RegisterToken.tsx	25.00%	9 Missing ⚠️
packages/frontend/src/hooks/useRegisterToken.ts	60.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
+ Coverage   87.64%   88.04%   +0.40%     
==========================================
  Files          26       26              
  Lines        1271     1255      -16     
  Branches      124      121       -3     
==========================================
- Hits         1114     1105       -9     
+ Misses        157      150       -7     

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