fix: defer email subscription state fetching

[wa0x6e]

Summary

A request is sent to the envelop API on page load, to retrieve whether the current user is already subscribed or not. This was made so that when the user click on the "Email subscription" menu, it open the correct modal.

This PR introduces a change, to defer this request to only triggered when the user click on the "Email subscription" menu, thus saving a request on each page load, for user not interested in the email subscription.

This change introduces a change on the UI:

• Since we don't know the user subscription state when he open "Email subscription" modal, a loading skeleton will be show until we get the state from envelop API, before showing the correct modal content.
• In the PostVoteModal, we will charge the user subscription status on mounting, so there will be a UI flash, where the "Subscribe to email" button will first not exist, then appear after status fetching
• Some minor margin adjustment for consistency: use m-4 and gap-4 everywhere

Closes: #4501

How to test

1. Load any page
2. It should not trigger any request to https://core.envelop.fyi/subscriber
3. Connect your wallet
4. Go to the user menu, and click on "Email subscription"
5. It should open a placeholder modal, and trigger a request to https://core.envelop.fyi/subscriber
6. Once the request succeed, it should show the correct modal content, depending on your subscription state
7. Closing the menu will trigger a request to https://core.envelop.fyi/subscriber, if you're already subscribed, or pending email verification (so next modal opening have correct state)
8. Reopening the email subscription modal should not trigger any request to https://core.envelop.fyi/subscriber, and should remember the previous state (so no placeholder modal anymore)

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Name	Status	Preview	Comments	Updated (UTC)
snapshot-testnet	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 13, 2024 3:13pm

[samuveth]

Works well, one thing I noticed is if I enter a wrong email address for verification there is no way to change it and the UI keeps showing the verify your email modal.

tACK

[wa0x6e]

Works well, one thing I noticed is if I enter a wrong email address for verification there is no way to change it and the UI keeps showing the verify your email modal.

tACK

Correct, need to add feature to resend verification email, and to change email

[wa0x6e]

Works well, one thing I noticed is if I enter a wrong email address for verification there is no way to change it and the UI keeps showing the verify your email modal.
tACK

Correct, need to add feature to resend verification email, and to change email

In fact, see #3904