[webauthn] Compress & Uncompress large blobs

This patch implements gzip compression and decompression for WebAuthn's
large blobs extension.

Compression needs to happen 1) when receiving a large blob through the
WebAuthn API, 2) when setting a large blob through the virtual
authenticator (exposed through webdriver and devtools) and 3) when
directly setting a large blob in unit tests. To satisfy the rule of two
for cases 1) and 2), this patch introduces a Gzipper interface to the
data decoder service, which runs in a sandboxed utility process. Case 3)
is simply handled by compressing in tests.

This feature is guarded behind the WebAuthenticationLargeBlobExtension
feature flag.

https://w3c.github.io/webauthn/#sctn-large-blob-extension

Bug: 1114875
Change-Id: I52c9031f1927a1bd4819d4d075fd59036fd3187a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2464011


Commit-Queue: Nina Satragno <nsatragno@chromium.org>
Reviewed-by: Adam Langley <agl@chromium.org>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817700}
GitOrigin-RevId: aed99fb1abbdccdb74de4992ba5c4100b6a382de