Merged PR 162: Implement symbols and other stuff (see desc)

Implement symbols
- Add, Remove, Select Container
- Form
- Link with container
- Symbol behavior application to container (move to x with xpositionreference)

Important changes
- Remove SelectedContainer from HistoryState, meaning that it will be slower for each load but will be faster for each operations* (SetHistory, SelectContainer, DeleteContainer, SymbolOperations)
- ElementsSidebar now opens with isSidebarOpen meaning that both sidebar will open on toggle
- Moved camelize, transformX, restoreX to different modules (stringtools.ts, svg.ts)

src/index.scss

@@ -11,6 +11,10 @@
     @apply transition-all px-2 py-6 text-sm rounded-lg bg-slate-300/60 hover:bg-slate-300
   }
 
+  .sidebar-component-card {
+    @apply transition-all overflow-hidden text-sm rounded-lg bg-slate-300/60 hover:bg-slate-300
+  }
+
   .elements-sidebar-row {
     @apply pl-6 pr-6 pt-2 pb-2 w-full
   }