LIMS-1068: Move discovery away from constructor, get cookie expiry dynamically

[gfrn]

JIRA ticket: LIMS-1068

Summary:

• Reduce number of calls to OIDC provider by only performing discovery when necessary
• Get expiration time for token from provider, apply it to cookie

Changes:

• Cookie expiry is applied based on value returned from OIDC provider
• Endpoint discovery is only performed when a function is called and there are no known endpoints

To test:

• Check if user logout behaves as expected
• Check if user login behaves as expected
• Check if opening page in a new tab doesn't trigger login
• Check if moving between pages works

[ndg63276]

LGTM