fix: add warning for long secret names (!359)

A start of a fix for coop-cloud/organising#463
Putting some code out to start a discussion.  I've added a linting rule for recipes to establish a general principal but I want to put some validation into cli/app/new.go as that's the point we have both the recipe and the domain and can say for sure whether or not the secret names lengths cause a problem but that will have to wait for a bit.  Let me know if I've missed the mark somewhere

Reviewed-on: coop-cloud/abra#359
Reviewed-by: decentral1se <decentral1se@noreply.git.coopcloud.tech>
Co-authored-by: Rich M <r.p.makepeace@gmail.com>
Co-committed-by: Rich M <r.p.makepeace@gmail.com>

pkg/secret/secret_test.go

@@ -28,3 +28,14 @@ func TestReadSecretsConfig(t *testing.T) {
 	assert.Equal(t, "v2", secretsFromConfig["test_pass_three"].Version)
 	assert.Equal(t, 0, secretsFromConfig["test_pass_three"].Length)
 }
+
+func TestReadSecretsConfigWithLongDomain(t *testing.T) {
+	composeFiles := []string{"./testdir/compose.yaml"}
+	_, err := ReadSecretsConfig("./testdir/.env.sample", composeFiles, "should_break_on_forty_eight_char_stack_nameeeeee")
+	if err == nil {
+		t.Fatal("Expected to fail")
+	}
+
+	// Check error
+	assert.Equal(t, "secret test_pass_one is > 64 chars when combined with should_break_on_forty_eight_char_stack_nameeeeee", err.Error())
+}