Fixed z-indexes of offline badge and cookie notification

[phoenixdev-kl]

Related issues

Item 1 (see below) fixes issues related to #2773.

Short description and why it's useful

1. The wish list and compare icons, which got added in PR Feature/#2773 #3157, overlap the offline badge. I adjusted the z-index of the badge to use the global setting for overlays (-1 to be displayed behind the overlay).
2. By fixing the offline badge I found that the cookie notification uses a hard coded z-index. In order to be consistent, I adjusted the z-index to also use the global overlays setting.
3. The text in the offline badge is not really centred, it overlaps the screen by 20 px.
4. My IDE told me "functionalities" isn't a word, so I changed the whole sentence. Later, after having pushed the changes, I found out that it actually is the correct plural of "functionality". The usage of this word seems to be quite controversial, though.

Screenshots of visual changes before/after (if there are any)

Before	After

Which environment this relates to

• Test version (https://test.storefrontcloud.io) - this is a new feature or improvement for Vue Storefront. I've created branch from develop branch and want to merge it back to develop
• RC version (https://next.storefrontcloud.io) - this is a stabilisation fix for Release Candidate of Vue Storefront. I've created branch from release branch and want to merge it back to release
• Stable version (https://demo.storefrontcloud.io) - this is an important fix for current stable version. I've created branch from hotfix or master branch and want to merge it back to hotfix

Upgrade Notes and Changelog

• No upgrade steps required (100% backward compatibility and no breaking changes)
• I've updated the Upgrade notes and Changelog on how to port existing VS sites with this new feature

Contribution and currently important rules acceptance

• I read and followed contribution rules

[pkarw]

Cool! Thanks!