Fetch userId from routes

[lucy-m]

Made quite a few changes so have put them all in a PR for you to look over ❤️

• Fetch userId from route params for LoanForm and Dashboard
• Fetch userId from search params for HomePage
• Need to pass userId into CompanyConnections component again
• Need to pass userId/onClick into the Header and CompanyLogo components in order to navigate back to the home page with the userId
• A few formatting changes in various places