ncm-metaconfig: rsyslog: Add condition support to all action types

[SamC-STFC]

The rsyslog module previously could not use conditional filters for every type of action, this change updates the templates and the schema to add a new condition field to the generic rsyslog action template. Whatever is put in the condition field will be inserted as the condition of an if block surrounding the action, which is generated using the existing action template.
This means that the condition field can now be added to any action.

This should not cause any backwards incompatibility, since the existing action template is still used to generate the action itself.

Example configuration

dict(
  'fwd',
  dict(
    'condition', "<condition>",
    ...
    )
)

Example output

if <condition> then {
  action(
    ...
  )
}