style: move package installation task to more appropriate place to make program flow more clear

tasks/install_callas_pdf_engine.yml

@@ -72,3 +72,8 @@
     - src: "/usr/lib/x86_64-linux-gnu/libstdc++.so.6"
       dest: "/usr/local/lib/callas_pdfEngine_SDK_x64/callas_pdfEngineSDK_x64_Linux_{{ vault_callas_sdk_version }}/lib/libstdc++.so.6"
   notify: run ldconfig to configure dynamic linker run-time bindings
+
+- name: install packages
+  apt:
+    name: "libstdc++-8-dev"
+    state: present