Add Placeholder for `Help Request` Index Page

[x] There is a file called 'HelpRequestsIndexPage.js' in the 'src/main/pages/HelpRequests' directory.
[x] The file export a react component with a basic layout, a title 'HelpRequest', and placeholder text.
[x] In 'App.js', there is a route linking the path '/helpRequests/list' to 'HelpRequestsIndexPage'
[x] Create test cases in file called 'HelpRequestsIndexPage.test.js' located in src/tests/pages/HelpRequests directory.

ucsb-cs156-f22 / team03-f22-6pm-3