Move Microsoft.IdentityModel.Tokens into full assembly unification

Depends on https://github.com/Azure/azure-functions-host/issues/8888

Once we are able to ensure that the host is using the latest version of this assembly, barring the time it takes to deploy an update, users should not hit the error reported in https://github.com/Azure/azure-functions-host/issues/7878. However, we would also like to prevent those errors from impacting apps during that deployment window. To do that, we should move to full unification of the assembly, so that the version from the host is always loaded. This would mean that the version specified by the app is not actually resolved temporarily, until the deployment completes.

Moving to full unification should only occur when we are already on the latest available version of the dependency.

The scope of this work item is limited to existing supported host versions at the time of this issue being filed. A different approach should be taken for any future breaking change opportunities.

Read the dependency issue at azure-functions-host#8888 and the reported failure at azure-functions-host#7878 first. Then trace how Microsoft.IdentityModel.Tokens is currently unified for the supported host versions in scope. Done means the host version is always loaded, but only after the dependency is already at its latest available version, preventing deployment-window errors.

Written by the indexing model from the issue text.