feat: ensure that packages that depend on a newer version of Keyman are not offered for iOS, Android

[mcdurdin]

The server won't offer it.

At least, that was in the original design. I haven't looked at this for a long time.

For Windows, for example:

api.keyman.com/script/windows/14.0/update/WindowsUpdateCheck.php

Lines 168 to 171 in 3de6116

	if(isset($KeyboardDownload->minKeymanVersion) && version_compare($KeyboardDownload->minKeymanVersion, $appVersion, '>')) {
	// New version of the keyboard doesn't run with the user's Keyman Desktop version
	return FALSE;
	}

General online update check, used only by Windows (and Developer) at this point:

api.keyman.com/tools/onlineupdate.php

Lines 175 to 178 in 8d9a115

	if(isset($KeyboardDownload->minKeymanVersion) && version_compare($KeyboardDownload->minKeymanVersion, $appVersion, '>')) {
	// New version of the keyboard doesn't run with the user's Keyman Desktop version
	return FALSE;
	}

And it looks like that was not implemented in Android or iOS package-version check. So that needs to be fixed in https://github.com/keymanapp/api.keyman.com/blob/8209e4212df69149f0c39d518359f04afcec0b1a/script/package-version/package-version.php and apps:

1. api.keyman.com API should only offer keyboard and package updates that are supported (we can handle this for apps older than 19.0 by treating a missing version parameter as '18.0').
2. apps should always include version parameter in their package-version query.

Originally posted by @mcdurdin in #13559