Content Consistency Updates (1.4.0)

[dstrukt]

Might make sense to merge this after @dennisreimann's latest changes.

These are just aesthetic changes, header sizes, paddings, etc... to make things consistent, been a lot easier to spot with the latest updates.

A few minor tweaks I'd like to improve with this PR, but I need some help with:

• Fix active state when "Account" is selected + sub-navigation @dennisreimann
• "Profile" -> "Account" on Account tabbed navigation
• Change "General Settings" to "General" in Store Settings & make it the first tab
• "Email Server" -> "Email" in Server Settings in tabbed menu, change the content title from "Email" -> "Email Server"

The first item will close out one of the issues (#3180).

Added "Language" section:

Moves API Key CTA to top right:

[pavlenex]

To answer questions, I agree with all except these two:

Move "Language" section in "Checkout Appearance" to "General" in Store Settings

No, because this isn't a store language it's the language of the checkout page, so it's appropriate where it is.

"Checkout Appearance" -> "Checkout" in Store Settings tabbed menu

I don't think we should change it, it communicates what it really is, the appearance of your checkout page. If we do checkout it may confuse people thinking it's payment method setting or something else.

[dstrukt]

Ahh good call on the Language, thought this was App wide, noted.

That's a good point, I think I just took issue with it because there were multiple types of modifications (language, invoice, appearance), but maybe it's just because that word doesn't feels like it captures everything.. but I have no alternative suggestions, so will drop the issue for now.

[NicolasDorier]

This probably break something in the CanSetupMail test ping @dennisreimann

[dstrukt]

Oh, wow the account text switch was more simple than I anticipated, thought more would be involved.

[dennisreimann]

All TODOs done now :)

The failing link check is unrelated - this one should be merged next, I'll then finish #3323 based on this.