feat: packages: allow per-host package conf

We want to be able to assert / de-assert the presence of certain
packages.

Note that the ansible-openwrt role already gives us an opkg cache
refresh.

inventory.yml

@@ -1,6 +1,16 @@
 openwrt:
   hosts:
     ap3825i2.lan:
+      packages:
+        - name: kmod-ath10k-ct
+          state: absent
+        - name: ath10k-firmware-qca988x-ct
+          state: absent
+        - name: kmod-ath10k
+          state: present
+        - name: ath10k-firmware-qca988x
+          state: present
+
       network:
         device:
         - name: br-lan

wireless-setup.yml

@@ -1,7 +1,13 @@
 - hosts: openwrt
   roles:
     - gekmihesg.openwrt
+
   tasks:
+    - name: Install the right packages
+      opkg:
+        name: "{{ item.name }}"
+        state: "{{ item.state }}"
+      loop: "{{ packages | default([]) }}"
 
     - name: Setup network devices
       uci: