Add support for `targetPercentile` RMF rule parameter

[samsymons]

Task/Issue URL: https://app.asana.com/0/0/1207234800675204/f Tech Design URL: CC:

Description:

Client PR for https://github.com/duckduckgo/BrowserServicesKit/pull/809.

This adds support for the targetPercentile feature of RMF.

Steps to test this PR:

1. This test involves testing with a custom RMF manifest - point your app at the manifest in this PR and check that the message shows (it has 90% likelihood of doing so, if it doesn't then reset your installation of the app and try again)
2. Now push a change to that PR to set the percentile very low and test that the message doesn't appear

Device Testing:

• [ ] iPhone SE (1st Gen)
• [ ] iPhone 8
• [ ] iPhone X
• [ ] iPhone 14 Pro
• [ ] iPad

OS Testing:

• [ ] iOS 14
• [ ] iOS 15
• [ ] iOS 16

Theme Testing:

• [ ] Light theme
• [ ] Dark theme

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Internal references:

Software Engineering Expectations Technical Design Template