Update workflows

Update the GitHub actions workflows using a subset of the changes
from the master branch, commit 620a977f22.  Cherry-picking each
relevant commit would have resulted in a large number of conflicts
so this change only applies a minimal set of useful updates.

- Added build-dependencies.txt and checkstyle-dependencies.txt
- Added reclaim_disk_space.sh script
- Minor changes to build steps
- Reduced ztest run time
- checkbashisms, mandoc, and cppcheck were not included to
  avoid additional backports
- Add exceptions for shellcheck

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

.github/workflows/scripts/reclaim_disk_space.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -eu
+
+# remove 4GiB of images
+sudo systemd-run docker system prune --force --all --volumes
+
+# remove unused software
+sudo systemd-run --wait rm -rf \
+  "$AGENT_TOOLSDIRECTORY" \
+  /opt/* \
+  /usr/local/* \
+  /usr/share/az* \
+  /usr/share/dotnet \
+  /usr/share/gradle* \
+  /usr/share/miniconda \
+  /usr/share/swift \
+  /var/lib/gems \
+  /var/lib/mysql \
+  /var/lib/snapd
+
+# trim the cleaned space
+sudo fstrim /