Role switching without page reloading

[AaronPlave]

Refactors role switching in the UI to eliminate the page refresh. Closes #1512, closes #1312. This PR is a proof of concept and the necessary changes have only been made on the plan, plans, and tags pages. If the direction is approved then all pages will receive the same refactoring.

Key Changes:

• Refactor user variable into a user store at the +layout.svelte level and pass the store down to child pages using the svelte context API. Loosely based off of this blog post https://dev.to/brendanmatkin/safe-sveltekit-stores-for-ssr-5a0h but there is a lot of discussion out there about the best ways to avoid data leakage in sveltekit SSR while still storing the server-provided state.
• Refactor changeRole route to recompute the user's permissibleQueries and rolePermissions based on the new role and return the updated user to the client.
• Use ActiveRole header on client -> server requests to override the requested active role in order to recompute the user cookie when changing role.
• Refactor Nav to directly access and update user store from svelte context in order to avoid boilerplate user update event handling in all pages to support role switching.
• Refactor subscribable to add/remove/update itself in a new subscription manager store, allowing for restarting of all active subscriptions when the user changes in order to refresh the connection with new user role
• Add a derived store and hidden div to indicate when all web socket connections are finished loading, will be used for test purposes as another gate to determine when the page is loaded.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud