Add the ability to set Patroni tags (including custom tags) at the host level

[vitabaks]

Related issue: #586

Added the ability to add tags for Patroni (including custom tags) at the host level in the inventory file.

• Variable: patroni_tags
  • tags for Patroni in "key=value" format separated by commas
• Doc: https://patroni.readthedocs.io/en/latest/yaml_configuration.html#tags

Example:

root@pgnode01:/# patronictl -c /etc/patroni/patroni.yml list
+ Cluster: postgres-cluster (7351028658196582445) --+-----------+-----------------+
| Member   | Host        | Role    | State     | TL | Lag in MB | Tags            |
+----------+-------------+---------+-----------+----+-----------+-----------------+
| pgnode01 | 10.172.0.20 | Leader  | running   |  2 |           | datacenter: dc1 |
| pgnode02 | 10.172.0.21 | Replica | streaming |  2 |         0 | datacenter: dc1 |
| pgnode03 | 10.172.0.22 | Replica | streaming |  2 |         0 | datacenter: dc2 |
+----------+-------------+---------+-----------+----+-----------+-----------------+