Add support for HTTPS compression

[NoisomePossum]

What does this PR do?

Adds support for compression when sending logs over HTTPS.

Motivation

Now that the function sends logs over HTTPS by default we should allow users to compress the logs.

[ajacquemot]

Why do we need to convert the data to a string here ?

[ajacquemot]

I think we'll recompress the same batch over and over on retries, we could probably do the compression outside of this method to avoid extra computations on network errors.

[NoisomePossum]

I went ahead and removed the try block.

For the casting to string, I was getting some type errors for a while from the gzip.compress function when trying to convert data to bytes and casting it to a string first seemed to fix it. I just tried again though without it and everything works ok. Must have been some other error I fixed inadvertently. 🤷‍♂

[ajacquemot]

Can this method throw an error ? If so, we probably want to catch it here https://github.com/DataDog/datadog-serverless-functions/pull/190/files#diff-618731ddf1c446ef45d09613cb4b189bR339 to avoid retrying indefinitely

[ajacquemot]

PR looks nice, thanks for working on this, I think we could probably have moved the encoding logic in DatadogClient to avoid re-encoding the payload for each retry.

[NoisomePossum]

I took a stab at putting the compression in DatadogClient but when I do that I get the encoding error I mentioned above : https://a.cl.ly/NQuvpL0k

I think that error gets solved when the compression happens in DatadogHTTPClient because the scrubbing function just before it converts the array of logs into a single string with join. I’m also wondering if the scrubbing would still work if you do the compression in DatadogClient because wouldn't that mean you're trying to scrub text from a string of bytes once you get to that level?