[native/web] change title of MessageReactionsModal to All reactions

Summary:
I am wrapping up the inline engagement redesign work right now, but didn't have the chance to work on redesigning the MessageReactionsModal. With the new inline engagement going to our old MessageReactionsModal felt a little jarring since the modal provides all the reactions to you and not just the reaction specific ones.

To make it a little less jarring I changed the title from "Reactions" to "All reactions" and I am hoping that this will make it more clear to the user that we are not showing the list of users for that specific reactions.

https://linear.app/comm/issue/ENG-3787/implement-a-redesign-for-message-reactions-modal is the task for this, and I am hoping to get to it whenever I have a free cycle

Test Plan:
Please see screenshots

native:

web:

Reviewers: atul, kamil

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8861