This changes how plugins handle CLI args:
- The `cliArgs` instance prop of a `Plugin` will never be `undefined`. If there are no args, the prop will be an empty object.
- The `cliArgs` instance prop of a `Plugin` will now contain default values, if any were provided by the `Plugin`'s schema.
This differs from how the same property is handled in drivers. To that end, I split `AppiumDriver#getCliArgsForExtension()` (previously `assignCliArgsToExtension()`) into two separate methods for clarity.
This change also contains a few associated improvements to tests and types.
This PR changes the shape of plugin classes as well as how CLI args get assigned.
- The `pluginName` static property has been removed. `name` is now assigned via the `BasePlugin` constructor, and is derived from the plugin name in the manifest. This means that an implementor only needs to provide a `pluginName` in the manifest, and the data is not duplicated. The value in this map (the plugin name) is used to instantiate the plugin, instead of passing static `pluginName` property into the constructor.
- CLI args are now passed in through the constructor instead of assigned to the plugin instance after the fact.
Implementation details:
`getActivePlugins()` and `getActiveDrivers()` now return a `Map` of an extension _class_ to an extension name. The key is _not_ an instance, and is effectively a singleton, so we are not at risk of a memory leak.
This change does not otherwise affect drivers.
This change modifies the type of `BasePlugin.newMethodMap`, adds a
parameter to the `MethodMap` type, and updates the base plugin TS
config for better incremental builds.
