Remove NetStandard 1.x

[TimothyMothra]

Parent: #1160

Net framework compatibility: https://docs.microsoft.com/en-us/dotnet/standard/net-standard

Note that all Test projects should target NetCore2.1 and NetCore3.1. #1769

Remove

• NetStandard 1.1
• NetStandard 1.3
• NetStandard 1.6

Replace With

• NetStandard 2.0
• NetStandard 2.1

Affected Projects (11 of 17)

• BASE
  • Microsoft.ApplicationInsights
  • ServerTelemetryChannel
• WEB
  • DependencyCollector
  • PerformanceCollector
  • WindowsServer
• LOGGING
  • DiagnosticSourceListener
  • EventSourceListener
  • Log4NetAppender
  • NLogTarget
  • TraceListener
• NETCORE
  • Microsoft.ApplicationInsights.AspNetCore

Affected Builds

• Gated build (ADO)
• Linux builds (yml)

Action Plan

• First, remove TargetFrameworks from Product. This immediately stops compiling the NetStandard 1.x Done
• Second, remove TargetFrameworks from Tests. Done
• Third, cleanup code. Remove preprocessors and delete code forks. It's important to do this one project at a time so we can thoroughly review. (this can be done at any time by anyone on the team)
  • PerformanceCollector is fractured into 6 different shared projects. (NetFull, NetStandard, NetStandard.Stubs, NetStandard16.Stubs, NetStandard20, NetStandard20Net45). After deleting NetStandard1.x, this needs to be refactored into only 2 shared projects (Perf.Shared.NetFull, Perf.Shared.NetStandard).

Risks

• I noticed right away that some projects currently ONLY compile to netstandard 1.x.

[TimothyMothra]

@eddynaka, i merged your first PR.
When you start working again, please work on PerformanceCollector by itself so we can thoroughly review.
Thanks :)

[TimothyMothra]

@eddynaka Next, can you remove the #IF NETCOREAPP1 code branches? These are mostly in our test classes.

I see NETCOREAPP1_0 and NETCOREAPP1_1 both in use

[eddynaka]

Sure!