Initial structure

[nigriMSFT]

Set up some initial structure to the project that includes the following:

• empty public header per platform
• empty static library per platform
• prepare-machine.ps1 tool
• build.ps1 tool
• CI pipeline that builds the library for all platforms
• dependabot

All of this was taken from https://github.com/microsoft/msquic and trimmed down. There may still be some unnecessary stuff that is lingering (especially the cmake stuff which is foreign to me), but I think this is a reasonable start.

[nigriMSFT]

Some initial files to spark any discussion on directory structure or anything else

[nibanks]

I'm fine with the directory structure. I assume we'll have a test directory too.