Make table cells editable

#### Is your feature request related to a problem? Please describe

I need to implement a table where its cells need to be editable by users

#### Describe the solution you'd like

I think it is best to have` editable=True` option in `ui.table_column`

#### Describe alternatives you've considered

I've tried to implement this using [ui.text(make_markdown_table)](https://wave.h2o.ai/docs/examples/table-markdown/)

#### Additional context

Add any other context or screenshots about the feature request here.

Start by reviewing the ui.table_column API and the existing markdown-table workaround shown in the issue. Define how the editable=True option should expose cell editing and how edits are committed; done when table cells can be edited through the option and the behavior is covered by the project's relevant tests.

Written by the indexing model from the issue text.