Port Windows PGO support to master (#9985)

Port Windows PGO support to master (#9985)

The bulk of this PR is a cherry-pick of commit fa02660 that shipped in
release/1.1.0, updating the build system support for PGO to support
consuming PGDs properly during release builds on Windows.

Also included are the following new changes:
* Skip restore of opdata if the requisite project.json is missing
* If the optdata package restore fails, fail the build.
* Add new build option: 'skiprestoreoptdata'

Note: This change doesn't by itself enable PGO in master yet, because
training data (optdata packages) for master don't exist on myget yet.
However, with these changes, the only step remaining to enable PGO
optimizations is to add a project.json referencing the correct optdata
package.