Allow for `package.json` deep merge to support more scenarios

When supporting addons from ember@3 up to ember@6, there needs to happen various changes here and there.

My current problem is roughly mentioned here: embroider-build/addon-blueprint#131
Basically the resolving `@ember/owner` in ember <> 4.12 - that in some scenarios is missresolved by the package manager, namely pnpm for me. That's why we are advised to use [`dependenciesMeta.*.injected`](https://pnpm.io/package_json#dependenciesmetainjected). However, that comes with a big downside for actually developing the addon and requires third-party-tools only to fix that.

A handy trick would be for CI to have that scenario modelled, in my case for older ember versions.
Here is my sample commit for that: https://github.com/gossi/ember-ability/pull/137/commits/9ecfd9b458be241294ce8ca80abf9dedfe3dc173 which adds a script and `dependenciesMeta` to some `package.json` - but that does not work, because only a couple of selected properties are overwritable, see: https://github.com/ember-cli/ember-try/blob/e0d196ee4030879bccda807d47c2eb1742182558/lib/dependency-manager-adapters/base.js#L142-L150

What about a deep merge instead and everybody is free to change what _they_ seem necessary for them?