Better error for missing install

[ZoteTheMighty]

Better elaboration for a common error where a foreman-managed tool is being used outside of a scope in which it's been defined as a tool dependency.

Old error looked like this:

pdoyle:~/dev/projects/foreman (better-error-for-missing-install)
$ selene
'selene' is not a known Foreman tool, but Foreman was invoked with its name.
You may not have this tool installed here, or your install may be broken.

New error looks like this:

pdoyle:~/dev/projects/foreman (better-error-for-missing-install)
$ selene
'selene' is not a known Foreman tool, but Foreman was invoked with its name.

To use this tool from C:\Users\pdoyle\dev\projects\foreman, declare it in a 'foreman.toml' file in the current directory or a parent directory.

Available Tools:
         rojo => github.com/rojo-rbx/rojo@^6.0
         stylua => github.com/johnnymorganz/stylua@^0.13.0
         darklua => gitlab.com/seaofvoices/darklua@^0.7.0

Additionally, this tees up a 1.0.4 release.

[amatosov-rbx]

LGTM 🎉