Add more binlogging

[crummel]

In trying to troubleshoot a couple build issues I realized that MSBuild binlogs were nice to have. This change adds binlogging everywhere we can without changing the submodules' build scripts. It also fixes up submodules' RepoBuilds so that they execute with the project directory as their current directory - this was the cause of getting random log files in the repos directory.

[omajid]

Instead of editing BuildCommand in individual repo files, would changing repos/dir.targets directly work? It contains lines like

<Exec Command="$(BuildCommand) $(RepoApiArgs) $(RedirectRepoOutputToLog)" WorkingDirectory="$(ProjectDirectory)" EnvironmentVariables="@(EnvironmentVariables)" />

[dagood]

I imagine some repos' build scripts don't accept /bl (or other arbitrary msbuild parameters) so it seems likely to take time to sort that out. Many of the changes in this PR also don't run through dir.target's target and run Exec calls directly, so they'd still be needed anyway.

I don't think we're hoping for more command consolidation in the repos for 2.1/2.2. Arcade will give us more consistent commands for master. Refactoring what we can would be nice for maintenance, but I think this PR is fine for now as an incremental diag helper.