Rules to check compatibility with PSCore6

[SteveL-MSFT]

Now that PSCore6 has compatibility with many Windows PowerShell .Net modules, we should start developing rules to validate if modules used, .Net api's used, or incompatible Windows PowerShell features (api's removed or changed).

[bergmeister]

@SteveL-MSFT For cmdlets, there is also ready the rule UseCompatibleCmdlets, therefore only the .net apis seem to be missing, maybe the .net core compatibility analyzer could be leveraged for that? PR 954 updates the rule files at least for PSCore 6.0.2