feat: Add support for kms key aliases

[Geun-Oh]

Hello Guys. I'm here to close issue #381

I already implemented core logic of alias to arn, and checked that it works well. you can excute it by making bin file with go install. There's an exmaple of it.

hello.enc.json

{
    "secret": "hello world"
}

$ sops --encrypt --kms=deployment-common hello.dec.json > hello.enc.json

and it comes like this.

hello.dec.json

{
    "secret": "ENC[AES256_GCM,data:8b5cb4UE...I4Q==,type:str]",
    "sops": {
        "kms": [
            {
                "arn": "deployment-common",
                "created_at": "2024-06-20T14:57:52Z",
                "enc": "AQICAHj1y+..../BQxGpwwM4Zwg==",
                "aws_profile": ""
            }
        ],
        "gcp_kms": null,
        "azure_kv": null,
        "hc_vault": null,
        "age": null,
        "lastmodified": "2024-06-20T14:57:52Z",
        "mac": "ENC[AES256_GCM,data:GaLp+/g...=,tag:d1Xw6Xp8C/8TZsnPzjPsZA==,type:str]",
        "pgp": null,
        "unencrypted_suffix": "_unencrypted",
        "version": "3.8.1"
    }
}

Now there is some tasks that should be resolved.

• [ ] add alias field (now it's sharing arn field)
• [ ] add regex of alias(maybe just a string. any idea will be welcomed) + region fetching at createKMSConfig()
• [ ] clean up redundant logic and optimization

Since I'm not an expert of Go. Please come an contribute together.