dconf: Convert boolean values into the format that dconf expects

Even though we warn users to be careful to specify GVariant strings
for values, a common error is to be trying to specify a boolean string
which ends up getting converted into a boolean by the YAML parser or
Ansible. Then it gets converted to "True" or "False", the string
representations of Python booleans, which are not valid GVariants.

Rather than just failing with an obscure error when this happens,
let's be more user-friendly and detect when the user has specified a
boolean and convert it into the correct GVariant forms, "true" or
"false", so it just works. There's no good reason to be more pedantic
than that.

plugins/modules/dconf.py

@@ -405,11 +405,23 @@ def main():
         argument_spec=dict(
             state=dict(default='present', choices=['present', 'absent', 'read']),
             key=dict(required=True, type='str', no_log=False),
-            value=dict(required=False, default=None, type='str'),
+            # Converted to str below after special handling of bool.
+            value=dict(required=False, default=None, type='raw'),
         ),
         supports_check_mode=True
     )
 
+    # Try to be forgiving about the user specifying a boolean as the value, or
+    # more accurately about the fact that YAML and Ansible are quite insistent
+    # about converting strings that look like booleans into booleans. Convert
+    # the boolean into a string of the type dconf will understand. Any type for
+    # the value other than boolean is just converted into a string directly.
+    if module.params['value'] is not None:
+        if isinstance(module.params['value'], bool):
+            module.params['value'] = 'true' if module.params['value'] else 'false'
+        else:
+            module.params['value'] = str(module.params['value'])
+
     if Variant is None:
         module.warn(
             'WARNING: The gi.repository Python library is not available; '