Re-do the build infrastructure

[Tratcher]

This is a complete replacement of the build infrastructure:

• Adding Arcade
• Removing Sake
• Switching to SDK style projects
• Build on azure pipelines
• Apply SDL

Follow ups:

• Release automation
• Publishing build artifacts to a feed
• Symbol publishing
• PR validation
• Subscribe for Arcade updates

Cut:

• LOC packages will be discontinued

Note, a lot of this was copied from reverse-proxy and aspnetcore, there are likely things that could be removed. Please let me know if you spot any.

[dougbu]

Lots of questions and I still have ~100 files to look at. Before I do that, can most of the C# files be blithely ignored❔ And, where did the new projects come from❔

[dougbu]

What requires a .NET SDK be installed w/o enforcing a version❔

Suggested change

	"tools": {
	"dotnet": "6.0.100"
	"sdk": {
	"version": "6.0.100"
	},
	"tools": {
	"dotnet": "6.0.100"

Might also be worthwhile adding "allowPrerelease" and "rollForward" values to make it easier to build on random people's machines.

[dougbu]

Oh, that's odd. Why does this repo have an official pipeline but nothing to validate public PRs❔

[dougbu]

• Release automation
• Publishing build artifacts to a feed
• Symbol publishing
• PR validation
• Subscribe for Arcade updates

Much of this list is external to the repo. Publishing is handled by adding a Maestro++ (darc) default channel and Arcade updates come through a Maestro++ subscription for example.

[wtgodbe]

I also ignored .cs file changes & deletions - looks mostly good, but you can remove most of the files copied over from Arcade

[Tratcher]

Oh, that's odd. Why does this repo have an official pipeline but nothing to validate public PRs❔

The CI used to be provided by old services that have been discontinued. Replacing it wasn't a priority given this project is in maintenance mode. It should be easier now that we're back on current infrastructure.

[wtgodbe]

Oh, that's odd. Why does this repo have an official pipeline but nothing to validate public PRs❔

I think @Tratcher just has to create one on https://dev.azure.com/dnceng/public/_build and link it to the .yml file - docs: https://github.com/dotnet/arcade/blob/main/Documentation/AzureDevOps/MovingFromDevDivToDncEng.md, https://github.com/dotnet/arcade/blob/main/Documentation/AzureDevOps/AzureDevOpsGuidance.md#pipelines. You should also set up the mirror bot to mirror the github repo to the azdo repo if you haven't already