v4.0.0: Add .NET 7, remove .NET 5

Added a target for .NET 7 and removed the out-of-support .NET 5 target.

v3.0.0: Release type/support phase update

Breaking CLI change: The .NET release cycle has now split the concept of "release type" (lts, sts) from "support phase" (preview, go-live, active, maintenance, eol). The CLI has been updated accordingly to support this split, such that you can now filter on --release-type or --support-phase when listing available SDKs to download.

v2.1.0

• Enabled SourceLink for debugging support.
• Updated package metadata so NuGet Package Explorer validates everything out as correct.
• Added more target frameworks (netcoreapp3.1, net5.0) so folks with only newer SDKs installed can still use the tool.

v2.0.1

Fixed list of installed SDKs when the path contains a space (#14).

v2.0.0

• Unified the dotnet sdk list command so it handles both local and remote SDK versions. Remote/available SDKs are no longer under dotnet sdk download list - it's now dotnet sdk list --available.
• global.json written by dotnet sdk set is indented to match standard dotnet new globaljson template.
• Added support for RC SDKs available for download.