Improve `/apply` page

[Pabl0cks]

Right now we only have the form, could make a few improvements to it and to the page:

• Add extra info before the form explaining more context about the community grant or how the apply-approval proccess will be.
• Migrate logic of submit button to "Community Grants" component. See #66

In the future we may delete "Ask amount" and set it to a fixed amount, or add the feature for admins to set/edit this field.

[carletex]

Let's close this for now.

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