Update react-table to v8 (#2131)

Updating react-table to v8. 
- Migrating the existing table to v8
- Preserving the visuals and logic

What's done?
- Cell components are moved under `Cells` folder
- Old styles for react-table-6 is removed.
- Old types are removed
- All logic was preserved
- Some cell components are removed for simplicity


Fixes: https://github.com/grafana/oss-big-tent-squad/issues/125

src/panel-triggers/components/Problems/constants.ts

@@ -0,0 +1,6 @@
+export const DEFAULT_OK_COLOR = 'rgb(56, 189, 113)';
+export const DEFAULT_PROBLEM_COLOR = 'rgb(215, 0, 0)';
+export const EVENT_POINT_SIZE = 16;
+export const INNER_POINT_SIZE = 0.6;
+export const HIGHLIGHTED_POINT_SIZE = 1.1;
+export const EVENT_REGION_HEIGHT = Math.round(EVENT_POINT_SIZE * 0.6);