@material compilation errors

So many errors! Here's a list of the categories of the bugs.

1. Package statements include the @, which is invalid, and the same in imports of these packages.
2. [Weird bug with generics in @material/base](https://kotlinlang.slack.com/archives/C0B8L3U69/p1601228582079600)
3. Missing and extraneous overrides. Like #175 but with (mostly) funs instead of vars. Here, the solution is clear - just remove (or add, depending on which error is showing up) the override
4. lib.dom.d.ts expects ProgessEvent to take one type variable, but the builtin ProgressEvent takes no generic parameter.

Dependency:
` implementation(npm("@material/button", "7.0.0", generateExternals = true))`

Start by reproducing the issue with implementation(npm("@material/button", "7.0.0", generateExternals = true)) and review the generated declarations for the four listed error categories. Use the linked Slack discussion for the @material/base generics issue; done means the package statements, generics, overrides, and ProgressEvent mismatch no longer produce the reported compilation errors.

Written by the indexing model from the issue text.