Arcade build scripts

[tmat]

Use more of Arcade bootstrapper functions.
Convert buildCoreClr to msbuildEngine parameter used by Arcade.
Update Initialize* functions to memoize their result.

Use build.ps1 only for builds that follow standard build pipeline structure (restore, build, pack, test, sign, publish). Add a separate script for testing determinism and move common functions down to build-utils.ps1.

Use standard build pipeline from Arcade (build.proj).

Change build.sh to match build.ps1 wherever possible.

[tmat]

@jaredpar PTAL

[jaredpar]