[landing] implemented investor page boilerplate

Summary:
Will not land until all diffs in the stack are accepted

Boilerplate includes: Adding Investor page to Footer, creating Investor page with title and subtitle

Next diffs:

1. Implement Investor Card component
2. Populate Investor Cards with data

Linear Task: ENG-1953
Figma: Investor Page

Test Plan:
Please view the screenshot to see the boilerplate UI of the investor page:

Reviewers: atul, rohan, abosh, ashoat

Reviewed By: atul, rohan, ashoat

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5302