Changes proposed in this Pull Request:

I found that wpcomsh was shipping with a large number of installer files in vendor and in the classmap:

These don't look relevant to anything we need to do. Tracing it down, this dependency was added here when adding linting commands to the repo: #90

It might have also been added here instead: a9a44f4

As far as I can tell, composer/installers lets you install plugins to places other than vendor/, but I don't see it being used here. @anomiex also ran into some issues from it being included here: Automattic/jetpack#37737 (comment)

I think that means this is only needed for development (if at all), and we don't need to be including this when shipping the plugin. I searched for instances of "installer" and don't see it being used anywhere.

How to test the changes in this Pull Request:

• Have you followed the Writing high-quality testing instructions guide?

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.