feat: add security group IDs to DAX module

[Pancham97]

Description

Description of what this PR does. What have you added or changed, and why? If it fixes a bug or resolves a feature request, be sure to link to that issue.

This PR aims to add the capability to attach existing Security Groups when creating a DAX cluster. Currently, the default Security Group is attached to the DAX cluster when putting it in a VPC.

I have also done a little house-keeping by

• Adding .dccache to the .gitignore file
• Sorting the IAM policies for the DynamoDB tables
• Updating the README.md file to include the updated usage

Review Checks

Please check if the PR fulfills these requirements:

Put an x in the boxes that apply, Remove any lines that do not apply

• 📝 The commit message is clear and descriptive
• 🔐 The Security Considerations section in the PR description is complete - Please do not remove this
• 📄 Documentation has been added / updated (for bug fixes / features)

Dependencies

Add links to any pull requests or documentation related to this pull request.

• N/A

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• No

The users of this module would need to pass the Security Group IDs from now on. The existing users would not be affected.

Security Considerations

Are there any other security or data concerns to be aware of?

Please discuss the security implications/considerations relevant to the proposed change.
This may include...

• security-relevant design decisions
• concerns
• important discussions
• implementation-specific guidance and pitfalls
• an outline of threats and risks and how they are being addressed.

• Security misconfiguration -- From now on, the user would know about the Security Group they are attaching

Types of change

What kind of change does this Pull Request introduce?
Put an x in the boxes that apply

• 🐛 Bugfix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 🛠 Adding or updating configuration files, development scripts etc.
• ♻️ Refactoring (no functional changes, no api changes)
• 🧹 Chore (removing redundant files, fixing typos etc.)
• 📄 Documentation Update
• ❓ Other (if none of the other choices apply)

If "Other" please specify

• N/A

Testing

Please include steps that the reviewer can follow in order to test the changes

1. Create a dummy Terraform file and set the source as git::https://github.com/Pancham97/terraform-modules.git//tags?ref=feat-add-security-group-to-dax
2. Run terraform init
3. Run terraform plan
4. You should be prompted to pass a list of strings for Security Group IDs