IHostingEnvironment's and IApplicationLifetime's marked obsolete and replaced

## IHostingEnvironment's and IApplicationLifetime's marked obsolete and replaced

New types have been introduced to replace exisiting `IHostingEnvironment` and `IApplicationLifetime` types.

### Version introduced

3.0

### Old behavior

There were two different `IHostingEnvironment` and `IApplicationLifetime` types from `Microsoft.Extensions.Hosting` and `Microsoft.AspNetCore.Hosting`.

### New behavior

The old types have been obsoleted and replaced by new types.

### Reason for change

When Microsoft.Extensions.Hosting was introduced in 2.1 some types like IHostingEnvironment and IApplicationLifetime were copied from Microsoft.AspNetCore.Hosting. Some 3.0 changes cause apps to include both the Microsoft.Extensions.Hosting and Microsoft.AspNetCore.Hosting namespaces. Any use of those duplicate types causes an "ambiguous reference" compiler error when both namespaces are referenced.

### Recommended action

Replaced any usages of the old types with the newly introduced types as below,

Obsolete types (warning):
Microsoft.Extensions.Hosting.IHostingEnvironment
Microsoft.AspNetCore.Hosting.IHostingEnvironment
Microsoft.Extensions.Hosting.IApplicationLifetime
Microsoft.AspNetCore.Hosting.IApplicationLifetime
Microsoft.Extensions.Hosting.EnvironmentName
Microsoft.AspNetCore.Hosting.EnvironmentName

New types:
Microsoft.Extensions.Hosting.IHostEnvironment
Microsoft.AspNetCore.Hosting.IWebHostEnvironment : IHostEnvironment
Microsoft.Extensions.Hosting.IHostApplicationLifetime
Microsoft.Extensions.Hosting.Environments

Note the new IHostEnvironment IsDevelopment, IsProduction, etc. extension methods are in the Microsoft.Extensions.Hosting namespace which may need to be added to your app.

### Category

ASP.NET Core

### Affected APIs

[Microsoft.Extensions.Hosting.IHostingEnvironment](https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.hosting.ihostingenvironment?view=aspnetcore-2.2)
[Microsoft.AspNetCore.Hosting.IHostingEnvironment](https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.hosting.ihostingenvironment?view=aspnetcore-2.2)
[Microsoft.Extensions.Hosting.IApplicationLifetime](https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.hosting.iapplicationlifetime?view=aspnetcore-2.2)
[Microsoft.AspNetCore.Hosting.IApplicationLifetime](https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.hosting.iapplicationlifetime?view=aspnetcore-2.2)
[Microsoft.Extensions.Hosting.EnvironmentName](https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.hosting.environmentname?view=aspnetcore-2.2)
[Microsoft.AspNetCore.Hosting.EnvironmentName](https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.hosting.environmentname?view=aspnetcore-2.2)



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#### Issue metadata

* Issue type: breaking-change

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IHostingEnvironment's and IApplicationLifetime's marked obsolete and replaced #14926