Add Nimble & Quick submodules.
Add Nimble & Quick to the workspace.
Remove Specta & Expecta from the workspace.
Remove Specta & Expecta from the targets.
Remove the Specta & Expecta submodules.
Revert 5700e38..5492886

This rolls back to commit 5700e3883965d0c88af32ce317b21af02c10d98a.
Use the wip Specta branch.