Feature: Allow configuring Compression Level

[antdking]

Currently, all the requirements are zipped using Deflate, at a compression level of 9.

for our bundle, this results in a file size of 21.5 mb, with sls package taking around 28 seconds.
Changing the compression level to 5 results in a 22.0mb bundle, with packaging taking around 11 seconds.

For us, this would be a quick win for reducing our deploy times.

Please allow for the compression level to be configurable.

It might also be worth reducing the default compression level, though this could be considered a breaking change