FR: Make firebase compatible with Yarn2 pnp and PNPM

Edit by @hsubox76 : Just to note this same issue affects PNPM and the same fix should address both.

### [REQUIRED] Describe the problem
I get an error when bundling with Yarn 2 and firebase:
```
(node:82642) [MODULE_NOT_FOUND] Error: @firebase/database tried to access @firebase/app, but it isn't declared in its dependencies; this makes the require call ambiguous and unsound.
```

#### Steps to reproduce:

I'm building a create-react-app application with yarn2 with pnp that depends on firebase, and it outputs the following error:
```
(node:82642) [MODULE_NOT_FOUND] Error: @firebase/database tried to access @firebase/app, but it isn't declared in its dependencies; this makes the require call ambiguous and unsound.
```