Merge `awsNuke` and `awsDefaults` Logics

[james00012]

Context/Background

Right now, you will notice that we have separate routes for awsNuke and awsDefaults:

• awsDefaults: nuking default VPCs
• awsNuke: nuking other resources

However, there seems to be quite a lot of changes we can merge and streamline.

• ec2.go file currently contains nuking operations for a lot of resources (e.g., internet gateway, subnet, route tables). Let's separate it out to individual resources.
• we support functionality on individual resources to support nuking default vs. non-default resources
• we make changes in awsDefaults to follow similar logic as awsNuke to nuke default resources.
• we deprecate awsDefaults and create a parameter or config in awsNuke to target default resources.