[3.x] [iOS] Support multiple plist types in plugin

[naithar]

Extends current iOS Plugin system and allows to set a specific type for Info.plist key-value pairs.
Implements godot-sdk-integrations/godot-ios-plugins#5
Doesn't break compatibility.

Currently supported types:

• string - used as a default if no type is specified
• integer
• boolean
• raw - allows to use arrays or dictionaries
• string_input - allows to set string value for a key when exporting.

Example

gdip config

[plist]
plist_default="string_value"
plist_string:string="string_value"
plist_integer:integer=101
plist_boolean:boolean=true
plist_raw:raw="
<array>
    <string>UIInterfaceOrientationPortrait</string>
</array>
"
plist_input:string_input="default_input"

Editor Export screen:

Exported Info.plist: