Draft: Resolve "Basic Text Only Formulas"

This MR is the first in a chain please see https://gitlab.com/bramw/baserow/-/issues/149#note_652871385 for more details. It is to be merged into the formula field v1 final MR .This MR only allows formulas which result in static text, can't reference other columns or any other more complex features.

See https://gitlab.com/bramw/baserow/-/merge_requests/360/diffs#f203017d1d1cb59420d742e2ae05650b9051ae65 for an overview of what the sub modules in the formula module are responsible for in this MR.

Important

The code in this MR goes under large changes in the next open MR for formulas. This MR should be used as a simple introduction to the concepts involved here. Because of the large set of changes in the next MR it might be worth giving detailed feedback on that next one and just using this one for understanding/seeing how a simple formula field works.

Closes #586 (closed)

Not being done in this MR but a later one

• changelog.md has been updated if required
• Documentation has been updated
• The UI/UX has been updated following UI Style Guide