Display Loading Spinner instead of Loading text

Business/User Value: As an explorer of Diem I want a more noticeable loading indicator so that I don't skim past it when it appears on the page in several places

### Acceptance Criteria
**GIVEN** I navigate to a valid address
**WHEN** the data is loading
**THEN** a loading spinner is displayed instead of just text

**DEV NOTES**
[Relevant technical notes that developers may ask you to add to the story during weekly prep meeting (pre-IPM or IPM); sometimes they may add these themselves or add them as tasks]

No files or tests are named. Start by locating the existing loading text in the TypeScript frontend and identify each place where it appears during loading; done means valid-address loading states consistently display a spinner instead of text.

Written by the indexing model from the issue text.