feat: Adds -gzipCompression level as backup flag

[devanbenz]

This should fix slow backups. Gives users the ability to specify different levels of compression with the trade-off of compression ratio vs. speed.

Adds:

    -gzipCompressionLevel <level>
            The level of gzip compression to use for portable backups. Options: default, full, speedy, none.
            "default" uses the standard gzip compression, "full" uses best compression ratio, "speedy" uses
            fastest compression, and "none" disables compression. Optional. Defaults to "default".

[davidby-influx]

One question

[davidby-influx]

LGTM