fix: do not disable create gallery button on gallery overview page

[patricio0312rev]

[galleries] create gallery button can be disabled on overview

Summary

• New optional disableIfNoNfts prop for CreateGalleryButton component.
• nftCount prop for CreateGalleryButton component is now optional since not every implementation will require it.
• As a result, this button will never be disabled in the Gallery Overview Page.

Note: Initially I tested just making the nftCount optional and just checking if it wasn't undefined and it had a value different than 0. However, using isTruthy also checks if the number is different than 0. So I decided to be explicit with the prop.

## Steps to reproduce

1. Run the app in local or testing_e2e mode.
2. Make sure your wallet has no galleries created.
3. Go to Galleries overview page (/galleries) and see the magic ✨

## Screenshots

1. Gallery overview page (with no galleries created):

2. Gallery overview page (with some galleries created):

3. My galleries page (desktop):

4. My galleries page (mobile):

Checklist

• I checked my UI changes against the design and there are no notable differences
• I checked my UI changes for any responsiveness issues
• I checked my (code) changes for obvious issues, debug statements and commented code
• I opened a corresponding card on Clickup for any remaining TODOs in my code
• I added a short description on how to test this PR (if necessary)
• I added a storybook entry for the component that was added (if necessary)
• Documentation (if necessary)
• Tests (if necessary)
• Ready to be merged