Increase default slippage from 2% to 3%, show Advanced Options by default

[dan437]

Explanation:

• Increase default slippage from 2% to 3%
• Increase slippage from 1% to 2%
• Always show Advanced Options

Manual testing steps:

• Click on the Swap button in the MetaMask extension
• See the Swap page with Advanced Options visible and 3% slippage tolerance selected by default

Screenshots:

Swap page: Advanced Options visible and 3% slippage tolerance selected by default

Verifying that the 3% slippage is send to the server:

Pre-popullating previously set custom value when going back to the Swap page:

All unit tests are green:

[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.

[danjm]

This change looks good, but actually reveals a pre-existing bug that I think should be addressed within this PR.

To see this bug on this branch:

• set the slippage to 2
• click "Review Swap"
• once on the "View Quote" screen click "Back"
• the selection will be defaulted back to 3, even though the fetchParams.slippage still equals 2

I've attached a file that shows a change that resolves that problem:
slippage-patch.txt

However, there will still be a similar problem if a custom amount is entered. That should be resolved too, I think.

[danjm]

One small issue to address, otherwise this code looks good

[danjm]

I think it might be best not to call setCustomValue in the callback to useState, as this is incidental to the purpose of this function. I think the intent of the code would be clearer if we added a callback to the useState call that sets up the customValue which would set the initial custom value to currentSlippage if currentSlippage is truthy but not equal to 2 or 3.

[dan437]

I like that!

[dan437]

Done.

[danjm]

LGTM!