refactor: update Finjs sample for 19, resolve issues

[MarielaTihova]

1. Fixed:

   1. Stop button. It was always showing as disabled
   2. Price column: colors were not visible
   3. Sliders: sliding didn't change the value

2. Cleanup and refactoring

   1. Removed unused imports
   2. Ordered code
   3. Got rid of some useRef usage
   4. Icons setup

3. What is left? (UPDATE: Resolved both issues with commit 5f235df)

   1. Chart in grid. Currently not showing because there is no field="chart"
   2. Slider initial state issue. Initial state is always 100 even if another value is set in the useState. Is this a known issue/bug and is there a workaround for it? It's not working in the old react version of the finjs sample either.