* upgrade aws roles
* test upgrade aws roles
* Initialize aws credential backend at mount time
* add a TODO
* create end-to-end test for builtin/credential/aws
* fix bug in initializer
* improve comments
* add Initialize() to logical.Backend
* use Initialize() in Core.enableCredentialInternal()
* use InitializeRequest to call Initialize()
* improve unit testing for framework.Backend
* call logical.Backend.Initialize() from all of the places that it needs to be called.
* implement backend.proto changes for logical.Backend.Initialize()
* persist current role storage version when upgrading aws roles
* format comments correctly
* improve comments
* use postUnseal funcs to initialize backends
* simplify test suite
* improve test suite
* simplify logic in aws role upgrade
* simplify aws credential initialization logic
* simplify logic in aws role upgrade
* use the core's activeContext for initialization
* refactor builtin/plugin/Backend
* use a goroutine to upgrade the aws roles
* misc improvements and cleanup
* do not run AWS role upgrade on DR Secondary
* always call logical.Backend.Initialize() when loading a plugin.
* improve comments
* on standbys and DR secondaries we do not want to run any kind of upgrade logic
* fix awsVersion struct
* clarify aws version upgrade
* make the upgrade logic for aws auth more explicit
* aws upgrade is now called from a switch
* fix fallthrough bug
* simplify logic
* simplify logic
* rename things
* introduce currentAwsVersion const to track aws version
* improve comments
* rearrange things once more
* conglomerate things into one function
* stub out aws auth initialize e2e test
* improve aws auth initialize e2e test
* finish aws auth initialize e2e test
* tinker with aws auth initialize e2e test
* tinker with aws auth initialize e2e test
* tinker with aws auth initialize e2e test
* fix typo in test suite
* simplify logic a tad
* rearrange assignment
* Fix a few lifecycle related issues in #7025 (#7075)
* Fix panic when plugin fails to load
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