closes #8039

Why

During the design review process, one of the suggestions was to add titles to the "Add Product" bottom sheets to give more context to the merchants.

This PR adds those titles for the template flow.

How

• Update BottomSheet component to be able to provide a title and a subtitle. The current titles were renamed to subtitles.
• Update the template bottom sheets to have titles.

Screenshots

Template 1	Template 2	Manual

Testing

Note

The feature is currently only visible to users in the experiment treatment group. In the Audience section of the template experiment model, go to Variations > Manual Assignment and use the bookmarklet to assign yourself (your a8c account) to the treatment group.

You will need to log in to the app with your a8c account to see the experiment while it is in staging (not launched to users yet).

Steps

• Launch the app in a store with less than 3 products and tap the Add Product CTA
• See that the bottom sheets have titles for product creation type & the template option bottom sheet.
• See that the manual option bottom sheet does not have a title.

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.