iOS: Support for managing proxies and certificate authorities

[baltpeter]

With this PR, I'm catching iOS up with the new features added for Android in #27.

This is based on #27, which needs to be merged first.

Functions implemented so far:

• installCertificateAuthority() and removeCertificateAuthority() to install or remove a certificate authority as a trusted root CA on the device. Caveat: For the CA to be trusted automatically, the user needs to perform a one-time setup step. (iOS: Support for managing certificate authorities #44)
• setProxy() to either set or disable the global proxy settings. (setProxy() function for Android and iOS #25)

Additionally implemented:

• stopApp() to force-stop an app. (stopApp() function for iOS #37)
• isAppInstalled() to check whether an app is already installed on the device. (iOS: Function to check whether app is installed #41)

Unrelated to the rest of the PR but also added here (since I didn't want to stack yet another PR):

• Retry starting Frida on Android if that fails to hopefully fix Starting frida might fail after device reset #32.
• Automatically install Frida in ensureDevice() on Android. The device preparation instructions on Android are now delightfully short. \o/ (Android: Automatically install Frida if necessary #39)

[zner0L]

I haven’t tested it on the device, yet, but this is what I found reading through the code.

[baltpeter]

This should probably be rebased on main after #27 is merged but before this is merged.

[zner0L]

Like I mentioned (tweaselORG/meta#22 (comment)) Frida crashes the SpringBoard on iOS 15.7.2, so I can not really test this properly (my other test devices have not arrived, yet).

[zner0L]

Since we found the problem in tweaselORG/meta#22, I was able to test this. mostly anyway, it seems that the Apps I download all seem to crash if I install them on the device. But that has nothing to do with the changes. Could you change the README and fix #55 while you're at it? Then we can merge!

[zner0L]

Just to document: I had a problem where apps wouldn't start because I had more than one mitmproxy CA on the device activated. I don't know how this could have happend, but I just deleted my .mitmproxy/ folder, so there would have been a different certificate.

[zner0L]

I tested it now successfully and it works. Great, thank you!