[miosix-gcc] Removed unused site templates, and regenerated screenshots

etc/config/site-templates.conf

views/resources/template_screenshots/AdaIDE.dark.png

views/resources/template_screenshots/AdaIDE.darkplus.png

views/resources/template_screenshots/AdaIDE.default.png

views/resources/template_screenshots/CCmake.dark.png

views/resources/template_screenshots/CCmake.darkplus.png

views/resources/template_screenshots/CCmake.default.png

...esources/template_screenshots/DiffofTwoCompilers.dark.png

...rces/template_screenshots/DiffofTwoCompilers.darkplus.png

...urces/template_screenshots/DiffofTwoCompilers.default.png

.../resources/template_screenshots/DiffofTwoSources.dark.png

...ources/template_screenshots/DiffofTwoSources.darkplus.png

...sources/template_screenshots/DiffofTwoSources.default.png

views/resources/template_screenshots/JavaIDE.dark.png

views/resources/template_screenshots/JavaIDE.darkplus.png

views/resources/template_screenshots/JavaIDE.default.png

views/resources/template_screenshots/LLVMIR.dark.png

views/resources/template_screenshots/LLVMIR.darkplus.png

views/resources/template_screenshots/LLVMIR.default.png

views/resources/template_screenshots/PascalIDE.dark.png