[FEATURE]: Refactor digitalocean_database_firewall

[stawii]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe

I cannot create rule for droplet.

Describe the solution you'd like

• rename var.firewall_rules to var_allowed_ip_addr
• add var.allowed_droplets_ids
• same for k8s, tags, apps

Describe alternatives you've considered

Anything else?

Check https://registry.terraform.io/providers/digitalocean/digitalocean/latest/docs/resources/database_firewall#type

[stawii]

Sync:

• [FEATURE]: Refactor digitalocean_database_firewall terraform-module-digitalocean-postgresql#6
• [FEATURE]: Refactor digitalocean_database_firewall #5
• [FEATURE]: Refactor digitalocean_database_firewall terraform-module-digitalocean-redis#4