shell: support more mustache tags #10043

Job	Run time
validate commits	10s
python linting	31s
Generate build matrix	7s
spelling	6s
bookworm - test-install	12m 41s
bookworm - 32 bit	12m 46s
noble - test-install	12m 48s
el9 - test-install	13m 28s
alpine - test-install	12m 13s
fedora40 - test-install	11m 39s
jammy - test-install	11m 38s
focal - py3.8	16m 48s
bookworm - gcc-12,content-s3,distcheck	19m 19s
fedora40 - clang-18	16m 55s
coverage	23m 57s
el8 - ascii	19m 19s
el8 - test-install	13m 33s
el8 - system,coverage	7m 25s
inception	21m 32s
flux-sched check	6m 51s
flux-pmix check	13m 8s
macos build only	2m 59s
flux-accounting check	4m 30s
flux-pam check	4m 10s
Generate docker manifest	1s
	4h 18m 34s

Provide feedback