Added page navigation (#209)

* Added navigation on page

* Removed useless log, added docs to navigator component

* Fixed duplicated variables, some changes in navigation functions, changed pages.twig and navigator.twig

* Added flatArray model, changed navigation functions

* Replaced page footer style to page.pcss

* Fixed generating flat array, when pages remove

* Removed useless generating

* Renamed flatArray model to pagesFlatArray, updated descriptions, renamed generate to regenerate, removed hardcoded key name in cache

* Changed styles naming and added margin for navigation

* Added ability to change nesting in flat array, fixed BEM

* Updated nesting parameter, fixed BEM

* Changed navigator component by passing objects, removed navigator wrapper

* Style navigator renamed to navigator__item

* Update src/backend/models/pagesFlatArray.ts

Co-authored-by: Peter Savchenko <specc.dev@gmail.com>

* Renamed navigator__item to navigator_item

* Deleted wrappers from navigator buttons, removed page__footer

Co-authored-by: Peter Savchenko <specc.dev@gmail.com>

src/frontend/styles/vars.pcss

@@ -1,6 +1,7 @@
 :root {
   --color-text-main: #313649;
   --color-text-second: #5d6068;
+  --color-direction-navigation: #717682;
   --color-line-gray: #E8E8EB;
   --color-link-active: #2071cc;
   --color-link-hover: #F3F6F8;
@@ -124,7 +125,7 @@
 
   --squircle {
     border-radius: 8px;
-    
+
     @supports(-webkit-mask-box-image: url('')){
       border-radius: 0;
       -webkit-mask-box-image: url("data:image/svg+xml,%3Csvg width='24' height='24' viewBox='0 0 24 24' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M0 10.3872C0 1.83334 1.83334 0 10.3872 0H13.6128C22.1667 0 24 1.83334 24 10.3872V13.6128C24 22.1667 22.1667 24 13.6128 24H10.3872C1.83334 24 0 22.1667 0 13.6128V10.3872Z' fill='black'/%3E%3C/svg%3E%0A") 48% 41% 37.9% 53.3%;;