[feature request] fish shell script devenv for new fisher plugins

[DerekNonGeneric]

In the original ask, all reqs had yet to be realized, but as i become more familiar w/ the fish ecosystem, i am noticing that it doesn't seem like a separate container image specifically for this task would need to be created.

Our original issue driving this project: #1 could be very minimally extended to also include the dependencies and tooling to carry out fish shell development tasks as well; we will have broadened our horizons (no longer exclusively or primarily Jekyll-oriented, but more of a devenv that would be suitable for typical OpenINF community members day-to-day development, maintenance, and testing activities).

[DerekNonGeneric]

As the majority of this fisher plugin development will be taking place in this repository, it would be worth taking a look at our current devenv added in 380f066 and seeing what it contains that may be missing from this Standard OpenINFer one that we have been building here.

[DerekNonGeneric]

Allow this comment for continuously-updated cataloguing:

• Docker-in-Docker
• fisher
• fish-tape