* [stable/telegraf] Configurable service account

By default the telegraf service runs with the default RBAC permissions
this PR adds the option to create a service account with configurable
rules.
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Move RBAD flag one level up
Co-Authored-By: Naseem <naseemkullah@gmail.com>
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Align templates with charts
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Update RBAC deployment conditional
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Make role and binding kind configurable
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Move comments about values
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Simplify (cluster)role values
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] prometheus input rules example
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Applied @naseemkullah suggestions
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>

* [stable/telegraf] Corrected bad copy pasta
Signed-off-by: Cees-Jan Kiewiet <ceesjank@gmail.com>
Co-authored-by: Naseem <naseemkullah@gmail.com>