fix: Disable next button if input is invalid for token approval

[blackdevelopa]

Development & PR Process

1. Follow MetaMask Mobile Coding Standards
2. Add release-xx label to identify the PR slated for a upcoming release (will be used in release discussion)
3. Add needs-dev-review label when work is completed
4. Add needs-qa label when dev review is completed
5. Add QA Passed label when QA has signed off

Description
When approving an erc20 token, if input has an error, disable next button. Ideally, this might not happen for most devices as the keyboard is set to numeric, however some android devices might still display alphabets.

Screenshots/Recordings
Before:

Screen.Recording.2023-06-19.at.13.02.10.mov

After

Screen.Recording.2023-06-19.at.13.00.54.mov

If applicable, add screenshots and/or recordings to visualize the before and after of your change

Issue

Progresses #6635

Checklist

• There is a related GitHub issue
• Tests are included if applicable
• Any added code is fully documented

[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.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

50.0% Coverage
0.0% Duplication

[seaona]

@blackdevelopa just 2 small comments from QA:

• Whenever we enter a negative number, I can see how the message below displays This contract allows the site to spend 654 from your current balance

• Whenever we enter a number in scientific notation, I can see how the message below displays a message as if the input was valid i.e. This contract allows the site to spend 10 from your current balance plus 990 you might have in the future..

I think in both cases we should show the standard message Only enter a number that you are comfortable with .... like we do in Extension. What do you think @blackdevelopa @bschorchit ?

[seaona]

After discussing with @blackdevelopa , we've decided that the copy changes can be made in the separate task below, as they are out of scope of this bug fix

https://github.com/MetaMask/MetaMask-planning/issues/685