Vala and Meson compilation controls

[hanaral]

Problem

Right now the official method of making elementary apps is via the native code editor, so there might as well be an easy way to compile elementary apps.

Proposal

Add cool controls to start a compilation script with meson, maybe even with integrated features specifically for target flatpak runtimes, archs and other useful app-making stuff.

Prior Art

elementary-ide used to have this: Panic's sexy code editor: