* Checkout v2: Configure countdown timer
This addresses feedback by @astupidmoose left [here](https://github.com/btcpayserver/btcpayserver/discussions/4308#discussioncomment-4438926): Make the countdown timer configurable with a minutes setting. This way the merchant has full control over when to display the timer. They could even set it to equal the invoice expiry, so that it is shown right from the beginning.
* Rename property and adjust wording
* Remove expiration percentage from Checkout v2
* Indent all JSON files with two spaces
* Upgrade Vue.js
* Cheat mode improvements
* Show payment details in case of expired invoice
* Add logo size recommendation
* Show clipboard copy hint cursor
* Improve info area and wording
* Update BIP21 wording
* Invoice details adjustments
* Remove form; switch payment methods via AJAX
* UI updates
* Decrease paddings to gain space
* Tighten up padding between logo mark and the store title text
* Add drop-shadow to the containers
* Wording
* Cheating improvements
* Improve footer spacing
* Cheating improvements
* Display addresses
* More improvements
* Expire invoices
* Customize invoice expiry
* Footer improvements
* Remove theme switch
* Remove non-existing sourcemap references
* Move inline JS to checkout.js file
* Plugin compatibility
See Kukks/btcpayserver#8
* Test fix
* Upgrade vue-i18next
* Extract translations into a separate file
* Round QR code borders
* Remove "Pay with Bitcoin" title in BIP21 case
* Add copy hint to payment details
* Cheating: Reduce margins
* Adjust dt color
* Hide addresses for first iteration
* Improve View Details button
* Make info section collapsible
* Revert original en locale file
* Checkout v2 tests
* Result view link fixes
* Fix BIP21 + lazy payment methods case
* More result page link improvements
* minor visual improvements
* Update clipboard code
Remove fallback for old browsers. https://caniuse.com/?search=navigator.clipboard
* Transition copy symbol
* Update info text color
* Invert dark neutral colors
Simplifies the dark theme quite a bit.
* copy adjustments
* updates QR border-radius
* Add option to remove logo
* More checkout v2 test cases
* JS improvements
* Remove leftovers
* Update test
* Fix links
* Update tests
* Update plugins integration
* Remove obsolete url code
* Minor view update
* Update JS to not use arrow functions
* Remove FormId from Checkout Appearance settings
* Add English-only hint and feedback link
* Checkout Appearance: Make options clearer, remove Custom CSS for v2
* Clipboard copy full URL instead of just address/BOLT11
* Upgrade JS libs, add content checks
* Add test for BIP21 setting with zero amount invoice
Co-authored-by: dstrukt <gfxdsign@gmail.com>
* Opt-in for new checkout
* Update wording
* Create invoice view update
* Remove jQuery from checkout testing code
* Checkout v2 basics
* WIP
* WIP 2
* Updates and fixes
* Updates
* Design updates
* More design updates
* Cheating and JS fixes
* Use checkout form id whenever invoices get created
* Improve email form handling
* Cleanups
* Payment method exclusion cases for Lightning and LNURL
TODO: Cases and implementation need to be discussed
* Introduce CheckoutType in API and replace UseNewCheckout in backend
Co-authored-by: nicolas.dorier <nicolas.dorier@gmail.com>
