Extended testing bindings

[Jonathan Jin]

Define a new Hydra/Transient-prefix for testing in Projectile projects. Namely, should have the following heads/suffixes:

• Manual, which would fall back to projectile-test-project;
• DWIM, which would:
  • If current buffer is an implementation buffer, find the corresponding test file (a la projectile-toggle-between-implementation-and-test) and pass that to the default test command;
  • If current buffer is a test buffer, pass buffer's file path to the default test command.

[Jonathan Jin]

If current buffer is a test buffer, pass buffer's file path to the default test command.

Could do something similar w/ Embark along the following lines:

• If current selection is an implementation file, pass the corresponding test file to projectile-test-project;
• If current selection is a test file, pass it to projectile-test-project.