Update on Server Conformance Tests and COLRv1 Incxfer Demo

Last week I started setting up the server conformance tests. Thus far I've
set up a single test that makes a basic request and checks various things
such as the response being well formed according to the spec. The current
code can be found here
<https://github.com/w3c/ift-server-tests/blob/main/test_server.py>.

The tests are run by providing the address of a server to be tested, for
example to test against the current demo server:

$ python3 test_server.py "
https://fonts.gstatic.com/experimental/patch_subset"
"/apache/roboto/Roboto-Regular.ttf"

I've already found a few deviations from the spec  which I've been fixing
(eg. added vcdiff support
<https://github.com/w3c/patch-subset-incxfer/pull/33>) alongside developing
the tests.

I've started compiling a list of all statements that use "must" in the spec
in a spreadsheet
<https://docs.google.com/spreadsheets/d/1A2NNNCt1BZkpcwmg8GwPldfsvOtjS6rBkLcUJTWBO5k/edit?usp=sharing&resourcekey=0-wlWBs1tRgfqzROcyeU55gA>
(request
edit access if you'd like to help with filling it out). This is still a
work in progress, but the idea is to list all statements which must have
tests from the spec and then track where in the conformance test suite that
statement is tested. Plus capture notes about changes needed to the
implementation and/or spec related to those statements.

On another topic, I've set up a second incxfer demo page that works on a
COLRv1 emoji font:
https://fonts.gstatic.com/experimental/patch_subset/colrv1.html. COLRv1 is
well suited for use with incremental transfer so this a great demonstration
of the potential byte savings in using incxfer with emoji fonts. COLRv1
support isn't enabled by default in chrome so you will need to set the COLR
v1 flag in chrome://flags for the demo to work.