[Android] Numeric keyboard should be able to process all available keys

[adrianknight89]

Description of Change

Android numeric keyboard displayed 14 keys (https://developer.xamarin.com/recipes/cross-platform/xamarin-forms/controls/choose-keyboard-for-entry/), but only the digits along with the dot character were processed. This ensures that all characters can be input.

Steps to verify changes:

• Install Google Keyboard from the play store
• Change your input language to Swedish
• Run sample code
• Initially, KeyListener should listen for the 14 keys.
• Change keyboard type by tapping on the button
• KeyListener should be set to the proper listener

InputType = InputTypes.ClassNumber | InputTypes.NumberFlagSigned | InputTypes.NumberFlagDecimal does not work (tested on S6 / M) probably because of Android fragmentation.

IMO, entry validation should be left to the developer (see user's request). The simplest way to validate numbers is with double.Parse(text, CultureInfo.CurrentCulture), but for whatever reason custom validation might be required or the UI might be tasked to react as the entry changes from a valid number to an invalid number or vice versa.

You might see this bug while testing the sample. Please note that this is an existing bug.

Bugs Fixed

• https://bugzilla.xamarin.com/show_bug.cgi?id=42000

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[adrianknight89]

@kingces95 Anything happening for this PR?

[hartez]

I've created PR 719 as a proposed alternative to this fix.