This adds the run_once option for the two handler types (shell and
command). The variables `prometheus_target_handler_command_run_once`
and `prometheus_target_handler_shell_run_once` are introduced to
control this behavior.

For this change a switch from the Ansible Handlers to regular tasks was
necessary to  enforce run_once behavior with delegated hosts. If you
don't rely on handler specific features such as deferring, nothing
changes when using the role.

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

The id property of the exporter is used for checking the default values
specified in `prometheus_target_exporter_defaults` variable.
However when both the `host` and the `path` fields are specified
manually in the `prometheus_target_exporter` list this id is never
looked up.
The way the templating was handled however, still resulted in an error
when leaving out the id field.
The templating code was now rewritten to allow for the following
exporter configuraion to run:

prometheus_target_exporter:
- { host: exporter_without_id, path: /opt/simple_target4.yml }

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

This will decrease the amount of redundant configuration for users by
allowing them to specify a general prefix on global / exporter / play
level

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

Add more distros to CI/CD and include them in the galaxy meta file.

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

This will change indentation in target files like:

- labels:
    exporter: node
  targets:
  - host:9100

to

- labels:
    exporter: node
  targets:
    - host:9100

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

Signed-off-by: Colin Wilk <colin.wilk@tum.de>