🪟 🎨 Improve empty state of resource pages

[timroes]

What

This changes the wording of the buttons in the empty resource view slighty, to be more actionable (Synced with Natalie around the wording for those) to get us towards eventually removing the separate onboarding page. The new wording is now:

• Connection: "Create your first connection"
• Source: "Connect your first source"
• Destination: "Connect your first destination"

How

• Move the button label into a property and specify it in the parent components. In genreal we should try passing through actual translated strings or <FormattedMessage/> components instead of passing through ids or even generate them inside the component, so we can eventually get closer to actually validate them statically (see https://github.com/airbytehq/airbyte-internal-issues/issues/588).
• Moved the bowtie image into the component folder since it's only used there, in accordance to our plan of not having assets in public anymore.

[josephkmh]

LGTM

[dizel852]

Code - LGTM
(Not tested locally)