Modifying default variables and config

Renamed variables for defaults:
- flatpak_method -> default_flatpak_method: system
- defaults.paths.prefix -> default_install_prefix: /usr/local
New variables:
- default_install_method: package

tasks/helpers/appimage.yml

@@ -0,0 +1,26 @@
+# vim: set filetype=yaml.ansible :
+---
+- name: Install appimage {{ pkg }}
+  become: "{{ ext_become }}"
+  block:
+    - name: Ensure appimage path exists
+      ansible.builtin.file:
+        path: "{{ path.appimage }}/{{ appimage_link_name }}"
+        mode: '0755'
+        state: directory
+
+    - name: Fetch appimage
+      become: "{{ ext_become }}"
+      ansible.builtin.get_url:
+        mode: '0755'
+        decompress: false
+        backup: true
+        url: "{{ appimage_url }}"
+        dest: "{{ path.appimage }}/{{ appimage_link_name }}/{{ appimage_file }}"
+
+    - name: Link appimage to bin
+      become: "{{ ext_become }}"
+      ansible.builtin.file:
+        state: link
+        src: "{{ path.appimage }}/{{ appimage_link_name }}/{{ appimage_file }}"
+        path: "{{ path.bindir }}/{{ appimage_link_name }}"