Remove script for building self-contained package

[maryamariyan]

Summary of the changes

• Removed RuntimeIdentifiers and self contained packaging related content in csproj
• Set SelfContained to false

Unsure if something else needs to be added,
Also unsure of how best to test the end to end on the extension side.

Related PRs:

• Allow rzls to launch using standard dotnet (Redo) by maryamariyan · Pull Request #6844 · dotnet/vscode-csharp (github.com)
• Allow rzls to launch using standard dotnet vscode-csharp#5855

[maryamariyan]

Here's some notes from looking a bit further into our build scripts:

In our publishing code I saw a reference to the comment below by @dsplaisted

• refers to https://github.com/dotnet/cli/issues/9221#issuecomment-387512008
• seems relevant only when we want to do self contained packaging

Usage:

• PublishAllRids gets used in AfterSolutionBuilds.targets
• and RidsPublishDir gets used in AfterSigning.targets to create zip files for each platform

--- UPDATE

After our offline discussion about platform specific vs agnostic, seems like we still need to be doing platform specific work so, as instructed I just removed the self contained bits and left everything else as-is

[davidwengier]

Strictly speaking we don't need to specify SelfContained=false, but I have no problem being specific.

seems like we still need to be doing platform specific work

Just my 2c, but even if this wasn't true, I would still be very very strongly in favour of doing any work related to that in a separate PR. Changing multiple variables at the same time just makes testing and validation so much harder. Thankfully the point is moot :)