fix: fail the step or job whose expression cannot be interpolated (#1199)

An expression that failed to evaluate was logged and replaced by an empty string, so a `run:` step executed an empty script and reported success. The same swallow covered `shell:`, `working-directory:`, step `env:`, `with:`, `uses:`, the job's `env:`, `container:`, `services:`, `runs-on:` and outputs, and a called workflow's `with:` and `secrets:`. Every interpolation now propagates its error as actions/runner does: step-level values fail the step, job-level values fail the job at setup, `timeout-minutes` logs the error and runs unbounded, and a job or step name keeps its source text.

`defaults.run` and a called workflow's inputs and secrets are resolved once at job setup with the job context rather than per step, and the job's image is resolved once, so host mode and `ImageOS` derive from the image the job started with.

Closes https://gitea.com/gitea/runner/issues/392
Closes https://gitea.com/gitea/runner/issues/555

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1199
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: bircni <bircni@icloud.com>

act/runner/step_test.go

@@ -160,7 +160,7 @@ func TestSetupEnv(t *testing.T) {
 	sm.On("getStepModel").Return(step)
 	sm.On("getEnv").Return(&env)
 
-	setupEnv(context.Background(), sm)
+	require.NoError(t, setupEnv(context.Background(), sm))
 
 	// These are commit or system specific
 	delete(env, "GITHUB_REF")