_api_features.json content is duplicated from upstream, not modified

[petemill]

In https://github.com/brave/brave-core/blob/v0.70.25/common/extensions/api/_api_features.json (and associated manifest and permissions json file), we're copy / pasting the content from chromium and adding Brave changes to it.

Whilst this was seen as beneficial over patching from a rebasing point of view, it can lead to not picking up upstream modifications to API permissions for various contexts. This can lead to browser breakage, web/extension-compat issues and security deviations.

Instead, we could either:

• Merge our json properties with chromium's json properties
• Or, run a script to modify (allows deleting items)