ci: coverage improvements

Use `expose_as` to link to the HTML report, and also attach the xml as a
cobertura artifact
11 jobs for ci in 7 minutes and 45 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #400359
aarch64 docker
build-aarch64

00:00:34

passed #400360
macos
build-macos

00:00:06

passed #400355
amd64 docker
build-ubuntu

00:00:43

passed #400356
amd64 docker
build-ubuntu-static

00:00:42

passed #400357
amd64 docker
build-win32

00:00:16

passed #400358
amd64 docker
build-win64

00:00:16

 
  Test
passed #400362
gpu
test-gpu

00:01:57

75.5406%
passed #400363
gpu
test-gpu-asan

00:01:50

passed #400364
gpu
test-gpu-msan

00:01:39

passed #400365
gpu
test-gpu-ubsan

00:01:33

passed #400361
amd64 docker
test-ubuntu-scan

00:00:32