Test demo-rollup commands in CI

[neysofu]

To generate the script:

$ cargo run --bin bashtestmd -- --input examples/demo-rollup/README.md --output script.sh --tag test-ci

Then, chmod +x script.sh and run with ./script.sh.

I will remove script.sh and update CI workflows if approved, but I'm leaving the script committed to facilitate reviews for now.

[codecov]

Codecov Report

Merging #851 (983e1d8) into nightly (d9e2075) will decrease coverage by 0.9%.
The diff coverage is 0.0%.

Files Changed	Coverage Δ
utils/bashtestmd/src/main.rs	0.0% <0.0%> (ø)

... and 1 file with indirect coverage changes

[preston-evans98]

LGTM! Should we add this into CI?

[neysofu]

Done! Merging.