Make use of nuget depreciation warnings

[thompson-tomo]

Is your feature request related to a problem? Please describe.

End users of the steeltoe packages should be able to tell in nuget which ones are deprecated & what alternative they should use.

Describe the solution you'd like

With the 4.0 release a number of packages will be deprecated for instance:

• Hystrix ANNOUNCEMENT: Steeltoe Hystrix is moving into maintenance mode and will not be included in Steeltoe 4.0 #1070
• credhub ANNOUNCEMENT: Steeltoe CredHub Client considering move to maintenance mode for 4.0 #1071

Thus packages should show a deprecation warning & suggest an alternative they should use ie Polly.

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Above list is not a complete & I nearly started implementing hystrix not knowing about the discontinuation.

https://learn.microsoft.com/en-us/nuget/nuget-org/deprecate-packages

[thompson-tomo]

In light of #1244 considerably more packages should be added to this list.