[EuiDataGrid] Remove capitalization from boolean schema

[andreadelrio]

We currently capitalize cells under the boolean schema. I think it'd make more sense to have it in lowercase. The ML recently sent a PR doing this in Kibana, probably a good idea to do it on our side too.

Relevant file

eui/src/components/datagrid/_data_grid_data_row.scss

Line 61 in 5e4c3e2

&.euiDataGridRowCell--boolean {

[cchaos]

I can a reason for wanting both, so I'd say that this should be a configurable option. It could even be a blanket option across all schemas in terms of deciding what text-transform to use (if any).

[Dishebh]

@cchaos @andreadelrio shall I give text-transform none here as is done in ML?

[hetanthakkar]

@cchaos I've submitted a PR for this issue. Could you please review it!?