[core, react, vue]: Enhancement - Add Sepolia testnet

[Adamj1232]

Description

Add Sepolia testnet to native support(chain icon and background color - both point to the Eth mainnet values)

Closes #1598

Checklist

• Increment the version field in package.json of the package you have made changes in following semantic versioning and using alpha release tagging
• Check the box that allows repo maintainers to update this PR
• Test locally to make sure this feature/fix works
• Run yarn check-all to confirm there are not any associated errors
• Confirm this PR passes Circle CI checks
• Add or update relevant information in the documentation

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Name	Status	Preview	Comments	Updated
web3-onboard-docs	❌ Failed (Inspect)			Mar 23, 2023 at 10:23PM (UTC)

[lnbc1QWFyb24]

Just a sneaky log in there to remove.

[lewis-kori]

@Adamj1232 Thank you so much for the amazing work.
Just one more thing I noticed.
The notification callback in the notify package doesn't receive events for the Sepolia test net. We use this to record payments, analytics among other things

I wasn't sure where to reach out with this.

[Adamj1232]

@lewis-kori We are very happy that you are enjoying web3-onboard!
We currently don't have transaction notifications running on Sepolia but it is on our roadmap and will be prepped as Goerli wind-down