feat(stdlib): Function for Converting Character Encodings

[powerumc]

Our system utilizes both legacy systems and the latest Linux distributions. Occasionally, we encounter systems that operate with non-UTF-8 settings. When logs are sent via TCP from these systems, all Korean strings encoded in EUC-KR become corrupted.

To address this issue, I've created a functions.
The function signature is as follows.

decode_charset(value, from_charset)
encode_charset(value, to_charset)

If this addition is beneficial for the VRL project, I would like to submit a pull request.

[pront]

Hi @powerumc, thank you for creating this issue.

This sound like a generic version to process chars and it could eventually replace functions like the following:

• https://vector.dev/docs/reference/vrl/functions/#encode_base16
• https://vector.dev/docs/reference/vrl/functions/#decode_base16

In general, this sounds like a good idea, and we would be happy to review your PR.

[powerumc]

I have created a PR for this issue. #1162
I would appreciate your review.