Parse secret inputs in reusable workflows (#41)

Secrets can be passed to reusable workflows, either explicitly by key or
implicitly by `inherit`:

https://docs.github.com/en/actions/using-workflows/reusing-workflows#using-inputs-and-secrets-in-a-reusable-workflow

Reviewed-on: https://gitea.com/gitea/act/pulls/41
Reviewed-by: Jason Song <[email protected]>
Co-authored-by: Galen Abell <[email protected]>
Co-committed-by: Galen Abell <[email protected]>

pkg/jobparser/testdata/has_secrets.in.yaml

@@ -0,0 +1,14 @@
+name: test
+jobs:
+  job1:
+    name: job1
+    runs-on: linux
+    uses: .gitea/workflows/build.yml
+    secrets:
+      secret: hideme
+
+  job2:
+    name: job2
+    runs-on: linux
+    uses: .gitea/workflows/build.yml
+    secrets: inherit

pkg/jobparser/testdata/has_secrets.out.yaml

@@ -0,0 +1,16 @@
+name: test
+jobs:
+  job1:
+    name: job1
+    runs-on: linux
+    uses: .gitea/workflows/build.yml
+    secrets:
+      secret: hideme
+---
+name: test
+jobs:
+  job2:
+    name: job2
+    runs-on: linux
+    uses: .gitea/workflows/build.yml
+    secrets: inherit