This adds opcodes and capabilities from this week's upstream kernel.

As of commit 53db28933 ("fuse: extend init flags"), the init message
has been extended to 104 bytes, with more flags added in a flags2
field.

Prepare for this by allowing _OP_INIT to have short reads.

Tested on Fedora 38 (Linux 6.4.14) and Fedora 34 (Linux 5.11)

Change-Id: I366ecda9e23f1a329134677075ee839674ff4c57