KNOX-3040 - Support multiple ways to verify JWT tokens

[moresandeep]

What changes were proposed in this pull request?

This PR adds the ability to validate a JWT token using multiple ways at the same time. Previously, we could only authenticate JWT token using either

1. PEM cert
2. JWKS url
3. Knox signing key
   With this PR, knox will validate the incoming JWT token using all the above mechanisms if they are configured.

example provider config

<provider>
            <role>federation</role>
            <name>JWTProvider</name>
            <enabled>true</enabled>
            <param>
                <name>knox.token.use.cookie</name>
                <value>true</value>
            </param>
			
            <param>
                <name>knox.token.jwks.url</name>
                <value>https://my.idp.com/oauth/.wellknown</value>
            </param>


            <param>
                <name>knox.token.verification.pem</name>
                <value>MIIDaDCCAlCgAwIBAgIJAKFjn6W+gdAXMA0GCSqGSIb3DQEBBQUAMF8xCzAJBgNVBAYTAlVTMQ0wC...</value>
            </param>

            <param>
                <name>jwt.expected.issuer</name>
                <value>https://my.idp.com/</value>
            </param>

            <param>
                <name>knox.token.use.cookie</name>
                <value>true</value>
            </param>
        </provider>

How was this patch tested?

This patch was tested locally.