Refactor auth handling wrapper

This MR refactors the authentication wrapper authentication.validate to make it easier to maintain. This effectively defines an 'api' for authentication types where they need to provide a '_request_has_xxx()method and a_validate_xxx()` method.

This also improves the error handling by attempting all authentication methods, and only if they all fail do we return the first error encountered. This should enable users who have an invalid scitoken but a valid X.509 cred to gain access.

changed milestone to %GWDataFind Server 1.2.0

added gwdatafind_server.authentication label

requested review from @duncan.meacher

assigned to @duncan.meacher

added 2 commits

• e6ce8d3e - 1 commit from branch computing/gwdatafind:master
• 38c193da - auth: refactor the auth wrapper

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added 1 commit

• 177f2004 - auth: refactor the auth wrapper

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approved this merge request

added 3 commits

• 177f2004...ffb88996 - 2 commits from branch computing/gwdatafind:master
• 56087b22 - auth: refactor the auth wrapper

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merged

mentioned in commit 28dd49f0