iOS: plist entitlements are overwritten when multiple plugins are installed (4.5.4 iOS engine)

[donnie-jp]

Related to https://issues.apache.org/jira/browse/CB-13496

Description

We updated our cordova ios engine version in our app from 4.3.1 -> 4.5.4 so we could support dynamic frameworks for a new plugin i.e. use the embed attribute [https://cordova.apache.org/docs/en/8.x/plugin_ref/spec.html#framework].

After updating I noticed that the ipa didn’t have the expected keychain-access-groups entitlements and the SSO login in our app failed (which relies on these entitlements), and it had been working previously. The expected keychain entry was being added to the plist when plugin A was added to the app but then deleted when plugin B was added.

Reproduction steps

Pre-requisite: a Cordova app with plugins A and B that both modify the keychain-access-groups entitlements

1. remove all plugins from app
2. add plugin A and confirm the entitlements has the expected keychain-access-groups entry
3. add plugin B

Expected: entitlements plist contains both plugin A's and B's keychain-access-groups entries

Actual: entitlements plist contains only plugin B's entry

Possible fix

CB-13496 looks to be related and applying the fix from there resolves my issue.

[donnie-jp]

The changes in #45 resolve this issue.