fix: QR code not displayed on first attempt to connect via Wallet Connect on desktop / chromium browsers

[blushi]

Description

Closes: #2275

There was something weird happening with our existing implementation (custom). It was working fine in most browsers (Firefox, Safari), except chromium based browsers when the dev tools wasn't open for some reason (#2275 (comment)).
So instead I've set it up so that we define a customModal for the cosmos-kit ChainProvider, this modal only gets displayed when trying to connect with wallet connect, since we only use cosmos-kit for that so far. This also seems like a cleaner solution anyway, which involves less custom code (see code diff stats).

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How to test

1. Go to https://deploy-preview-2279--regen-marketplace.netlify.app/ from desktop
2. Click the login button and try to connect with Wallet Connect
3. You should see the QR code
4. Scan from Keplr mobile and approve
5. You should be connected

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📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

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[blushi]

we needed to move the ThemeProvider up so the LoginModalMobile provided as walletModal to ChainProvider renders with our MUI theme

[blushi]

@paul121 @erikalogie please see testing instructions above

[paul121]

This is better... although I did experience the same issue the very first time I loaded the page and clicked WC. Loading the page again, however, and it works. You can test this in an incognito window. Clearing local storage for this site will also "reset" this and cause the error on next load.

The modal doesn't seem to have everything it needs the first time it loads. But subsequent loads are fine. I think it makes sense how these changes fixed the subsequent loads. Any idea for the first load?

[aaronc]

When I tested in Safari, the modal got stuck on the loading animation the first time I tried this. Then the second time I clicked, I saw a QR code right away.

[blushi]

@paul121 @aaronc this should be fixed now

[erikalogie]

LGTM!