Our current top crasher is an unclear error when ProcessManager fails to resolve an executable path. To fix this, we'd like to being adjusting the process resolution logic and adding more instrumentation to track failures. In order to begin the process, the ProcessManager has been folded back into the flutter tool
Some of the null-safety commands were missing - plumb them through. Ensure that verbose mode shows their output, and clean up the messaging around sound-null-safety.
Fixes#59769
Adds a test that validate each of the null safety supporting build commands has everything plumbed through.
