feat(organizations): add theming/story for Mantine Loader and LoadingOverlay TASK-1464

[pauloamorimbr]

🗒️ Checklist

1. run linter locally
2. update all related docs (API, README, inline, etc.), if any
3. draft PR with a title <type>(<scope>)<!>: <title> TASK-1234
4. tag PR: at least frontend or backend unless it's global
5. fill in the template below and delete template comments
6. review thyself: read the diff and repro the preview as written
7. open PR & confirm that CI passes
8. request reviewers, if needed
9. delete this section before merging

📣 Summary

Theming for Mantine's Loader and LoadingOverlay was added to match Kobo's current LoadingSpinner for general purpose.

📖 Description

Both 'regular' and 'big' variant were added with its respective type names to be used with Mantine's Loader and LoadingOverlay components.
To simplify the implementation I decided to simply use the existing LoadingSpinner component instead of extracting it's contents.
Since Mantine's Loader doesn't have the message parameter, right now I'm fixing it on false so it won't appear. We may need to implement a Wrapper in the future to add a message, depending on our future needs.

• LoadingOverlay is already in use at feat(organizations): add theming/story for Mantine Select TASK-1379 #5414

👀 Preview steps

• Use storybook to check the visual of the component and compare with the existing loader in use in the app.

[jamesrkiger]

Should we deprecate this?
https://github.com/kobotoolbox/kpi/blob/pamorim/task-1464-mantine-theme-for-loader/jsapp/js/components/common/loadingSpinner.stories.tsx

Other than that, looks good to me.

[pauloamorimbr]

Should we deprecate this? https://github.com/kobotoolbox/kpi/blob/pamorim/task-1464-mantine-theme-for-loader/jsapp/js/components/common/loadingSpinner.stories.tsx

Other than that, looks good to me.

I don't think so... I'm just using the default mantine component, which does not use the message parameter. Instead of deprecating the current one with a message we should probably make a wrap so Mantine's one would properly replace it.