Terraform plan diff improvements

[serdardalgic]

This PR addresses some of the problems mentioned in #98

• allowed_ip_ranges and pg_config will be TypeSet because their order might change and that had generated unnecessary changes in the plan output This has been moved to fix: Make allowedIpRanges and pgConfig TypeSet #128, see the comment below for the reasons.
• storage throughput value in biganimal_cluster resource is now computed because it is automatically calculated by BigAnimal based on the IOPS input.
• DiffSuppressFunc is set for IOPS field of the storage. If there is no initial value, and it already has a set value in the state, it won't show any diff for this field.

These changes require a Minor bump and they don't require any state migrations.

Please review.

[serdardalgic]

As stated in the Example Major Number Increments section of the Versioning Best Practices document:

Changing attribute type where the new type is functionally incompatible (including but not limited to changing TypeSet to TypeList and TypeList to TypeSet)
would required a Major version bump.

That's why, I'd like to remove this change from this PR and add a separate PR for that change.
We can include that change before a major bump. The next major bump will be our way to 1.0.0 which would (quoting the same document above)

Version numbers above 1.0.0 signify stronger compatibility guarantees, based on the rules above.

Probably we might have some more groundbreaking changes before our 1.0.0 releases, to name a few

• Update the authentication to use refresh_token for a more maintainable authentication experience #41
• Upgrade to terraform plugin framework.  #117

[mbiagetti]

LGTM