WebUI Page Title should be descriptive

[itaigilo]

Currently, the page title in the WebUI remains "lakeFS", no matter what sub-page you're in -
Which makes navigation with a lot of open tabs very difficult.

Page title should be more descriptive, for example:

• "my-repo | lakeFS"
• "my-repo / my-branch | lakeFS"
• "Pull Requests - my-repo | lakeFS"
• "Administration | lakeFS"