Placeholder for the Lend page

[brozorec]

Context

At the private launch, the lending vaults won't be available but we want to keep a reference to this feature. We have already implemented on the markets page a "Coming soon" tab for "Lending". However, clicking on the "Lend" section in the header leads to a 404 error. We want to add a similar placeholder for "/lend" as for the markets page.

TODOs

• [x] simplify the placeholder component and comment out the connection and the email (keep only the image, the title and the message)
• [x] implement in my-positions, the exact same way
• [x] take the placeholder component from the markets page and bring it to the page "/lend"

The text is not final and might be changed in the future.

[ferostabio]

Hey @NikolaiYurchenko in case you didn't notice, just added another item to the task.