webui: Don't use inline functional component for router's Switch to avoid unnecessary re-renders.

[junhaoliao]

References

Internally it was found that collapsing / expanding the sidebar would clear the search results. Further investigation found that the search page was re-rendered when the isSidebarCollapsed state variable got updated, causing unnecessary and undesired re-render of page contents.

It was also identified that the pseudo user authentication system is no longer in use and can be removed.

Description

1. Remove user login methods and related UI components.
2. Rename React root component to root which is a more standard convention.
    

Validation performed

1. cd <PROJECT_ROOT>; task
2. cd ./build/clp-package/sbin; ./start-clp.sh
3. ./compress.sh ~/samples/hive-24hr/i-00c90a0f/
4. Opened the WebUI address in a browser.
5. Started a query with string 123 and observed the job finished and the results are displayed in the results table.
6. Clicked the "Collapse" button to collapse the sidebar and observed the results still present within the search page.
7. Clicked the "Expand" button to expand the sidebar and observed the results still present within the search page.

[junhaoliao]

Please put this review on hold. Let me also remove the unused user authentication system in this PR instead.

[junhaoliao]

The changes are pushed, and the PR descriptions have been updated. Please resume the review.

[kirkrodrigues]

How about:

webui: Don't use an expression to render routes to avoid unnecessary re-renders. (#336)

(At least that's my understanding of the issue.)

[junhaoliao]

How about:

webui: Don't use an expression to render routes to avoid unnecessary re-renders. (#336)

(At least that's my understanding of the issue.)

JSX itself is an expression, but sometimes React is smart enough to avoid re-evaluation of the JSX. The initial fix does exactly that although the routeSwtich constant was later inlined. Supposedly another fix is to keep the <Routes/> as a component and move it out of the <App/>.

It might be more clear to say webui: Avoid unnecessary React route-switch re-render within functional components. (#336). What do you think?