refactor(auth): eliminate OVMF-style CamelCase from FilterSignatureList

[beshleman]

uefistored uses snake_case, not CamelCase.

Signed-off-by: Bobby Eshleman bobby.eshleman@gmail.com

[stormi]

So, I know it's a simple change, but sometimes bugs hide in that so:

• was that code tested manually?
• is that code tested in the unit tests of the project?
• can you give testing instructions for me or someone else to test the modified codepaths?

[beshleman]

So, I know it's a simple change, but sometimes bugs hide in that so:

* was that code tested manually?

* is that code tested in the unit tests of the project?

* can you give testing instructions for me or someone else to test the modified codepaths?

It is tested by the test_db_append test and by installing/reinstalling the Windows KB4535680 update.

More surgical testing of this requires appending the db or dbx variables. An example might be:

1. Given a db containing certificates A, B, and C:
   1. Appending an auth file containing certificates D should result in db=A, B, C, D.
   2. Appending an auth file containing certificate A should result the db unchanged (A, B, and C)
   3. Appending with an empty auth file should result in the db unchanged (A, B, C).

An example of making the auth files using efitools, see: https://github.com/xcp-ng/uefistored/blob/windows-kb4535680/scripts/certs/create-certs.sh

Then they may be installed from inside the guest using efi-updatevar.

The /opt/xensource/libexec/create-auth tool may be used to build the auth files too.

[stormi]

Note: it's too late for 8.2.1 but we can do it for future releases

[benjamreis]

Not a problem, it's a coding style PR so not urgent at all. I'm just trying to not let it rot.

[benjamreis]

Unit tests locally succesfull in the docker. (Again the GH action failed on a mitrror thing...)

[benjamreis]

XCP-ng tests successful on Alpine, Debian 10 & Windows 10 (with efitools)