Backport PR-9713 & PR-9711 for Magento 2.1 - Google Analytics fixes when Cookie Restrictions is enabled

[hostep]

cherry picked from commits:

• a4daf56
• 058f287

Description

• Backport of stringify cookie value to fix Google Analyitcs Tracking and Cookie Overlay #5596 #9713 for Magento 2.1
• Backport of Cookie Restriction Mode Overlay should not be cached by Varnish #6455 #9711 for Magento 2.1

I also took over the reformatting of that line introduced in 391bf42

Fixed Issues (if relevant)

1. Google Universal Analytics does not track when Cookie Restriction is enabled  #5596: Google Universal Analytics does not track when Cookie Restriction is enabled
2. Google Analytics Tracking Code cached by Varnish if Cookie Restriction Settings are active #6441: Google Analytics Tracking Code cached by Varnish if Cookie Restriction Settings are active
3. Cookie Restriction Mode Overlay is cached by Varnish #6455: Cookie Restriction Mode Overlay is cached by Varnish

@bka: do you recommend to also include #9711 in Magento 2.1, it seems like these two PR's are related?
I only backported #9713 for now, because it fixed a specific issue in our case, we didn't need #9711 to fix our issue (we aren't using Varnish, that might explain it), but it might make sense to include both of these in Magento 2.1?

Update: added backport for PR #9711 and updated the issues list above with more issues involved with these fixes

[ishakhsuvarov]

@hostep I've been testing #9711 and #9713 and they seem to be pretty related (as far as I remember I was only able to succeed with testing by applying both together). I'm pretty sure #9711 not only relates to Varnish but to built-in page cache as well.

[hostep]

@ishakhsuvarov: thanks for the very fast review and test!

I added #9711 as a new commit to this PR.

[ishakhsuvarov]

@hostep Haven't tested this PR yet, just sharing my experience from previous testing.
Thanks for the update.