Add `devsrv` shell script for convenient, env-based execution of LiquiDoc

I have been working on a Bash script called `devsrv`, which I use locally when playing with Codewriting, and now with more formal LDCMF projects. When it is truly a general-applicatin LDCMF utility, I will add it to the boilerplate (this repo) and share it with everyone. This will likely replace your commonly used `bundle exec liquidoc -c _configs/build-docs.yml --etc --etc` commands, first establishing default options based on the deployment environment.

Basic environments will include:

**dev** Running simply `sh devsrv` will execute a local build and Jekyll serve operation, by default running no tests.

**stage** This build runs tests. Use `sh devsrv stage --serve-after` to spin up a local instance once tests are run. Try `sh devsrv stage 4001 --serve-after` to spin up a local instance at port `:4001` instead of default port. The `stage` build is probably what is run during continuous deployment ops during draft reviews.

**search** Pushes updated records to appropriate Algolia cloud search indices. Possibly run manually or under certain conditions by the deployment ops.

**prod** The final product, only to be as part of deployment ops.

The script also allows the passing of version ranges: `sh devsrv 3.2-4.5`, to generate just that range of docs versions.

Lots of other operations enable modifications of the standard environments.

Start by reviewing the existing `bundle exec liquidoc -c _configs/build-docs.yml` workflow and `_configs/build-docs.yml`, then define the proposed `devsrv` command's environment modes and arguments. The work is complete when the script supports the described dev, stage, search, and prod operations, including version ranges and `--serve-after` port handling.

Written by the indexing model from the issue text.