[META]: Feature Roadmap

I think we've done a good job of making `ember-light-table` feature rich and extensible.
Opening this issue to create an open area for discussion around where we see ELT going and to give transparency to the community as to what they can expect in some sort of future.

### Large Features Under Pseudo-active Development
- Modular behaviors + Keyboard support https://github.com/offirgolan/ember-light-table/pull/347
- Integrate vertical collection for rendering performance. Work being done [here](https://github.com/alexander-alvarez/ember-light-table/tree/vertical-collection) for https://github.com/offirgolan/ember-light-table/issues/435

### Roadmap
- Proper Horizontal Scroll #284
- Freezing/Fixed columns (after vertical collection is implemented) (like the sticky columns in https://github.com/offirgolan/ember-light-table/issues/434)
- Sticky rows https://github.com/offirgolan/ember-light-table/issues/434
- "Out of the box" column and cell types
- I'd like to see the community pool together their best / most common cell and column patterns and share these with each other so we have an out of the box set, and if the need arises plugin-packs for different columns/cell combos
- ... \

Any and all suggestions are welcome.