Install option which causes failure if .tool-versions lists unknown plugin

**Is your feature request related to a problem? Please describe.**

I had an issue where my app wouldn't build correctly in CI because a plugin that was listed in `.tool-versions` hadn't been previously installed as a plugin. In this case it was pretty clear what the issue was because I got a `No such file or directory` error for the command (though the *reason* wasn't super clear, since it was part of migrating to GitHub actions and I thought that while I had installed it one step, maybe the state didn't carry over to the next step or something; took me a while to realize that `asdf` silently ignores unknown plug-ins). However, I can imagine a *much* more insidious version of this problem where, say `python 3.7` is ignored and it falls back to system python or something like that.

**Describe the solution you'd like**

I would like a flag to `asdf install`, perhaps `--expect-plugins`, that would cause the command to exit with a failure status code if it detects a plugin in `.tool-versions` (I think, *any* `.tool-versions` in the ancestor chain, but maybe just the current directory?) that hasn't previously been added. That would have made my CI issue immediately apparent.

At work, we've standardized across teams on `asdf` among our dozens of apps, and it's second nature to do `asdf install` when working on a new project. So I'd probably use this flag by default all the time, just so I know right away if some team's project introduces a new plugin.

**Describe similar asdf features and why they are not sufficient**

I've found a number of issues related to unknown plugins in `.tool-versions`. Most propose some version of automatically installing those plugins. While I personally would prefer that solution, I know that it's been rejected. However, I haven't found my specific proposal here in any other issues, and I think it might be acceptable where the others weren't.

**Describe workarounds you've considered**

I suppose a shell script that I can alias `asdf install` to.

**Additional context**

If this solution is acceptable, I'd be happy to work on a PR for it.

Start at the asdf install command entry point and inspect how .tool-versions files and unknown plugins are handled. Resolve whether ancestor directories are included, then verify that the proposed opt-in flag exits unsuccessfully when a listed plugin has not been added while preserving current behavior without the flag.

Written by the indexing model from the issue text.