Use hexToDecimal to parse gasLimit in send footer

[ghost]

Fixes: #10919

Explanation:
The gasLimit is being represented as an unprefixed hexadecimal string every render after the first. This means the comparison to 5208 is just comparing to NaN in a lot of cases which are incidentally passing.

In the issue 300000 and 300001 are flagged as numbers that fail when they should not, but there are also quite a few that pass when they shouldn't too, like 1000.

To fix, gasLimit is now parsed to a decimal and compared to 21000.

Manual testing steps:

• On develop branch, send a transaction with the advanced gas controls
  • Verify the "Next" button is disabled for gas limits of 300000 and 300001
  • Verify the "Next" button is not disabled for a gas limit of 1000
• On this branch do the same and verify the opposite for each one

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[ghost]

I have read the CLA Document and I hereby sign the CLA

[brad-decker]

@JackAldridge thanks for the contribution. Would you be interested in testing your findings with the work done in #10965 ? Regardless i'd love to get your work landed ahead of that change as I definitely encountered this problem during said refactor and you should get your 'contributor' tag :D

[brad-decker]

Go ahead and rebase on develop and push those changes up so we can get a build going.

[ghost]

Okay just rebased, and yep I can take a look at that refactor later today

[ghost]

@brad-decker just got round to looking at that other PR and can confirm it fixes all the issues I looked at.

Unless it's urgent maybe we should just wait for that one to land? Getting unit test failures here and not familiar enough with the test suite to tell if it's actually related to these changes.

[brad-decker]

The unit tests are failing legitimately due to our tests using "mockGasLimit" 😬 it's entirely up to you. I can jump in here tomorrow and clean up those tests and get your commit landed ahead of my changes. I'm also okay if you want to close this. In any event thanks for taking a look at the refactor! Appreciate all the eyes I can get on it 😊

[ghost]

Cool, I'm going to close this one then. Thanks for taking a look