Fix gzip Decompression Support

[BJap]

Currently, gzip decompression fails. I noticed when trying to decompress RESTful content bytes in my project that uses gzip for content-type that the headers are not read correctly and I get a failure message of -3.

I suspected I could get around this by slicing the byte array of the raw content. I came across a comment from @FoamyGuy , whom knowingly or not, also found this bug, and had the same idea. That workaround also works in my own code.

I know there are some tests in tests/circuitpython/zlib_decompress.py, but not sure how these things are done here.

My project partner and I worked together to come up with the solution shown in this PR. The tested inputs used are the the same text input compressed each using deflate gzip, and zlib. The new code can reverse each into the original decompressed text. These are included below:

---

deflate: dtst.txt

b'\x0b\xc9HU(,\xcdL\xceVH*\xca/\xcfSH\xcb\xafP\xc8*\xcd-(V\xc8/K-R(\x01J\xe7$VU*\x94gd\x96\xa4*\xa4\xe4\xa7+\x18\x1a\x19\x9b\x98\x9a\x99[X\x1a(\x94d\xe6\xa6\x16\xeb\x01\x00'

---

gzip: gtst.txt

b'\x1f\x8b\x08\x08\x94\xaf\xead\x00\x03tst.txt\x00\x0b\xc9HU(,\xcdL\xceVH*\xca/\xcfSH\xcb\xafP\xc8*\xcd-(V\xc8/K-R(\x01J\xe7$VU*\x94gd\x96\xa4*\xa4\xe4\xa7+\x18\x1a\x19\x9b\x98\x9a\x99[X\x1a(\x94d\xe6\xa6\x16\xeb\x01\x00\xbe\x98\x07*C\x00\x00\x00'

---

zlib: ztst.txt

b'x\x9c\x0b\xc9HU(,\xcdL\xceVH*\xca/\xcfSH\xcb\xafP\xc8*\xcd-(V\xc8/K-R(\x01J\xe7$VU*\x94gd\x96\xa4*\xa4\xe4\xa7+\x18\x1a\x19\x9b\x98\x9a\x99[X\x1a(\x94d\xe6\xa6\x16\xeb\x01\x00.x\x16\xb8'

---

decompressed: tst.txt

b'The quick brown fox jumps over the lazy white dog 1234567890 times.'

[gamblor21]

I have not got a chance to test this yet, but just wanted to leave my quick comment after looking it over.
I had left GZIP on the original as we were discussing better ways to include it. I do not see any downside to including this change to allow those who want to the ability to use it a bit easier.

Issue #6284 has some discussion about changes in micropython about uzlib and at some point it is worth looking at those and an overall plan for decompression in circuitpython. I just do not have the time to dig into that deeper now.

[tannewt]

Isn't this implementation being used: https://github.com/adafruit/circuitpython/blob/main/shared-bindings/zlib/__init__.c#L51 ?

[tannewt]

Looks good! Thanks!