bug(iOS): the keyboard appears while installing a new language on the keyboard

**Describe the bug**

There are more than one way to add a new language to a keyboard (i.e. `sil_cameroon_qwerty`) which has already been installed on your device.

One of the way is to install from .kmp, but opening it from the `Files` app. Assuming that you have already had `sil_cameroon_qwerty` keyboard installed on your device and you would like to add a new available language to the keyboard, say `Aghem`.

When Keyman is inactive, go to where `sil_cameroon_qwerty.kmp` is located, tap on the file and you would see an unexpected error where the keyboard itself shows up at the bottom of the screen during the whole process of adding the new language, see the screenshot below.

after tapping on the .kmp:

after clicking on `Next`:

after clicking on `Install`:

What should have been shown instead is the one without the OSK, see below:

**Expected behavior**

The OSK should not be shown during the installation processes.

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**Keyman for iPhone:**
- Device: iPhone 8
- OS: 14.5
- Keyman version: from the build on this PR https://github.com/keymanapp/keyman/pull/5698.
- Target application: Keyman

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**Keyboard**
- Keyboard name: `sil_cameroon_qwerty.kmp `
- Keyboard version: 6.0.5
- Language name: Afade, Aghem