* UI: Deprecate the custom CSS options
As discussed with @pavlenex we are deprecating the custom CSS options for particular entities (payemnt request, pull payment, POS, crowdfund) in favor of the store branding approach.
This displays the custom CSS section only if these values are set already.
* Add IDs to html element
This will allow styling of individual entities.
* Payment Request: Improve public view
Closes#4450.
* Test fix
* Extract Vue utils
* Improve payment history
* Fix amount display
* Unify receipt and payment request tables
* Re-add text confirmation for copying to clipboard
* Minor print optimizations
* Wording: Rename Description to Memo
* Open view links in new window
* View updates
