Widevine plugin doesn't copy binaries

[andrej-repisky]

The Shaka player embedded plugin in Widevine CMD repo doesn't work as described in this readme paragraph:

## Shaka Player Embedded Plugin

This repository also provides a plugin that can be used to automatically add
Widevine support to [Shaka Player Embedded][].  All you need to do is use the
`dev_cdm.json` or `release_cdm.json` files and pass them to the `./configure`
script of Shaka Player Embedded.  For example:

./configure --ios --eme-impl ~/prebuilt_cdm/shaka_plugin/dev_cdm.json

The certificate will be handled automatically and the resulting Shaka Player
Embedded framework bundle will contain the embedded Widevine CDM.  This means
the resulting Shaka Player Embedded framework is usable by itself.

The resulting shaka player build directory doesn't contain Widevine CDM anywhere.

Build Environment

Shaka player emb., commit dabbeb5
Widevine CDM 5.2.4
Xcode 12.4

[TheModMaker]

I didn't update the docs there when I fixed #63. You need to manually add the CDM to your app's frameworks in addition to Shaka embedded's two frameworks.

[TheModMaker]

I've updated the CDM docs. One thing we should do is to copy the correct CDM to the build directory. That would at least make it easier for people to find the correct one. For now you need to find the correct version in the lib folder of the CDM repo.