Include JWT sub field in logs

[ahmadelrouby]

In reference to #1051

• Separated the decoding and authorization phases of a JWT token
• Added a new middleware that performs the decoding and stores the claims as part of the request
• Use request context to query the JWT's Subject value and dump them in the JSON logs
• Added a flag in the context to indicate previous decoding (avoid breaking existing interface)

[linux-foundation-easycla]

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[ahmadelrouby]

As shown in the screenshot, the field req_sub contains the subject "fake_uss" created for this specific token.