Adding IdToken claims to MSAL JS interfaces : AuthResponse and Account

[sameerag]

This PR:

• adds all the claims in an id_token in the API surface for the developer reference; idToken in 'Account' is to map a request to the corresponding session. This PR deprecates the current parameter 'idToken' in the 'Account' class and adds a more meaningful parameter: 'idTokenClaims'. Since both are same, for backward compatibility until 1.1.0, both the parameters are supported.
• adds 'idTokenClaims' in response to map the claims within a request-response cycle.
• remove dependency on response.idToken in UserAgentApplication code.

Relevant changes:

• Corresponding changes in response in UserAgentApplication
• Unit tests added for claims; more enhancement in UserAgentApplication test cases
• Unit tests added for IdToken and Account classes

Todo:

• Documentation changes needed for the Surface changes will be edited in the Readme once this PR is ready to be Merged.
• Today we have two different data types for IdToken and AccessToken. Ideally, both should have been tokens (JWT format as referenced in Microsoft AAD docs). Since this is a breaking change, we are preserving the IdToken type in the response for this PR but will track this in the future major release.

[pkanher617]

LGTM.

[jasonnutter]

One comment otherwise looks good!