feat: (IAC-367) Allow Ability To Specify Which Availability Zones the Subnets Get Created In

[jarpat]

Changes

Allows users the ability to specify which AZs that the subnet gets created in with the new subnet_azs variable.

Similar to the existing subnets the map lets to set the name of the subnet along with zones will be used during creation

subnet_azs = {
  "private"  : ["us-east-2c", "us-east-2b"],
  "public"   : ["us-east-2a", "us-east-2b"],
  "database" : ["us-east-2a", "us-east-2b"]
}

So if your defined subnets as so in your .tfvars

{
  "private" : ["192.168.0.0/18", "192.168.64.0/18"],
  "public" : ["192.168.129.0/25", "192.168.129.128/25"],
  "database" : ["192.168.128.0/25", "192.168.128.128/25"]
}

for "private" : ["192.168.0.0/18", "192.168.64.0/18"], the first subnet will be created in us-east-2c and the second in us-east-2b

This variable is entirely optional, and if not defined the code will perform a lookup to populate the zones just like the behavior in viya4-iac-aws:7.2.1 and prior. If entire keys are not defined, the lookup will be used to populate those. Also, If not enough zones are defined in the subnet_azs in comparison to the subnets map a the zone lookup will be done to make up the difference. (behavior removed)

Test

WIP

[thpang]

Need to review the need to add or change what the customer is providing.

[thpang]

The code now takes what the customer provided an augments that value, i.e. its not what the customer provided, its a very well educated guess and provides what's needed, but it simply covers up the user error in that they did not provide the correct number of items for this element. Need a discussion on this.

[jarpat]

I agree, it may be better not to correct or append to the user input and let it fail, the user should correct any mistakes made.
This should be a quick update to the local.tf + doc , I'll make the change and test it out.

[jarpat]

Updated the behavior, no longer correcting user input and will let it fail instead. The user should be responsible for correct input. Docs and locals.tf changed, performing tests.

[jarpat]

Closing this PR, need to rebase and rework this slightly after the most recent changes from IAC-1174.