Run cargo commands using package name instead of pushing into directory

[heaths]

Since all our crates are in a single workspace, it's better that the pipeline commands (scripts, etc.) pass --package (short: -p) when supported because:

1. It's easier to see what package a command was run on if there's a failure (have to hunt for the directory we pushed into otherwise most times),
2. It's less maintenance and risk pushing into directories and popping on errors (it's rare, but I've seen the pop fail to be executed).

[heaths]

Note that, for eng/scripts/Test-Packages.ps1, the package info should already have the package name. If anything, the manifest directory name should match the crate name, though it's best to read the crate name from the manifest if needed.