Add alias for MP S3 KMS key

[dms1981]

Tracked upstream by #7569.

This PR adds a name_prefixed KMS alias to identify the KMS key used by the bastion module. A forthcoming PR will add unit tests.

[github-actions]

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Setting default tflint config...
Running tflint --init...
Installing "terraform" plugin...
Installed "terraform" (source: github.com/terraform-linters/tflint-ruleset-terraform, version: 0.9.1)
tflint will check the following folders:

Trivy Scan Success

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Trivy will check the following folders:

[github-actions]

Trivy Scan Success

Show Output

```hcl

---

Trivy will check the following folders:

</details> #### `Checkov Scan` Success
<details><summary>Show Output</summary>

```hcl

*****************************

Checkov will check the following folders:

CTFLint Scan Success

Show Output

*****************************

Setting default tflint config...
Running tflint --init...
Installing "terraform" plugin...
Installed "terraform" (source: github.com/terraform-linters/tflint-ruleset-terraform, version: 0.9.1)
tflint will check the following folders:

Trivy Scan Success

Show Output

*****************************

Trivy will check the following folders: