feat: add user profile page, improve search

[chriswhong]

Adds user profile routes with two dataset lists:

• user datasets /:username
• datasets the user is following /:username/following

Both lists share query params of type UserProfileParams. Introduces a new pattern for query params:

1. on mount or update, read query params from URL
2. convert params from the URL into valid UserProfileParams by adding default values
3. fetch data using UserProfileParams
4. when user interacts with pagination, query, or sort, etc, modify the UserProfileParams
5. update the URL with a "cleaned" version of UserProfileParams, (excluding default values)
6. go to 1

Updates Search to use the same pattern for query params.

TODO:

• improve loading states
• add a sticky header on scroll
• handle no results (e.g. user doesn't follow any datasets)

[ramfox]

One or two style nits I think should be changed, and some questions about naming of our listing params, but since that is an ongoing conversation anyway, not something that needs to be fixed right now: LGMT