Moves class definition out of the file that contains the main function
Introduces IconServiceInterface. It is used by menu to convert icon-names to actual file locations.

Currently the interface has two implementation
First is Mirror - It returns the file name as the icon name. It is default for amm::menu
The second is PredeterminedExtension - It appends .png when the file name doesn't have .png. .xpm or .svg extension
Adds a service::icon::Scan

In future it would search for icon files in file-system
Removes unused file includes from test sources
Search for icon paths by icon names in hard-coded locations

1. Test if the icon name is an absolute path to a file. If yes, use it.
2. Test if the icon name has an extension png, sgv or xpm. If no append the extensions one by one to the icon name.
3. Search for icon with extension in certain (as of now) hard-coded location. If found, use it.
4. If all searches fail return the icon name as it is.

The file lookups are implemented using stat.