Add support for build command arguments to the build html action

The build action takes an input for the path to the build command, and defers actual building to that command.

Since paths can contain spaces, the path is quoted when invoked.

But that means you can't give arguments to the build command, because they'll end up inside the quotes.

A new input for arguments would allow for more flexibility.

For example, I wanted to use this in a different project that has a Makefile for building, and I wanted to give arguments to the `make` command, but couldn't do so. Instead I committed a `build.sh` to call `make` with the arguments.

Start by locating the build HTML action definition and the input that supplies the build command. Trace how that command is invoked and how paths are quoted, then inspect any available action or workflow checks. Done means a separate arguments input can be passed to the build command without breaking paths containing spaces.

Written by the indexing model from the issue text.