Contribution flow: VAT UX improvements

[Betree]

Resolve opencollective/opencollective#1812

UX

Automatically retrieve user country from IP address.

UI

• Add a placeholder Please select a country if none selected (if IP resolution fails)
• Hide tax amount if no country selected
• Grey total if no country selected

[vercel]

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[xdamman]

This is awesome! :-)

Can it be "Please select your country" and "Enter VAT number (if you have one)"
Can you remove the VAT percentage next to each country in the dropdown?

Can "Please select your country" be much more visible than grey? Because it's basically the only thing that is blocking the user from continuing the process, so we should drive the user attention to that spot somehow.

[Betree]

• Use primary color for placeholder and replace "a country" by "your country"

• Remove percentages from countries list

• Update enter VAT number label