Improve XSS security

[jcary741]

What I am changing

• Removing Bootstrap script loaded from Minnesota DNR site, switched to a well-known CDN.
• Adding subresource integrity attributes for all script tags / css links to improve cross-site scripting on domains which deploy titiler html pages.

How I did it

How you can test it

Should only need to verify the generated API pages all still look / function as expected.