[e.cash] Add id param and better comments to H3 component

Summary:
Adding some better comments and an optional id paramater to the H3 component.
This will allow for adding a CSS id to any H3, which will be needed for some anchor links in other diffs
Also added method to verify its a proper id and test to test it

Test Plan:
npm run dev
go to core-tech page
inspect element on the 'AVALANCHE' title, and check it has no id assigned to it
Then add an id={title} to the H3 instance in TextImageBlock on the core-tech page
inspect the element again and should see id="AVALANCHE" on the h3
then npm test

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D14059