Add support for writing back to SF from QGIS

[sfc-gh-ecuberojimenez]

• Added execute sql action in data items
• Added new schema action in data items
• Added new table action in data items
• Added Custom widget for custom QgsProcessingAlgorithm
• Added execute query to data source provider
• Added tasks for sql query to layer
• Added svgs for dialog window icons
• Added data source manager widget, new schema dialog, new table dialog and sql query dialog as ui files
• Added .gitignore file
• Updated Makefile for new resource file
• Added processing algorithm