Highlight syntax in shell blocks as bash

[ivan-aksamentov]

Currently shell blocks are treated as strings. Would be nice if they could have syntax highlighting for shell scripts instead. Bash is probably the most common.

rule:
    shell:
       """
       what="world"
       echo "Hello ${what}"
       """

rule:
    run: shell("echo Hello world")

[alpha-beta-soup]

As in the linked issue, snakefmt enforces a linebreak preceding these codeblocks. This removes syntax highlighting that otherwise works. It would be good to have syntax highlighting in both cases.