initial generated tsconfig - add buildOnSave and compileOnSave with their defaults

[GabiGrin]

Usually I build typescript using a custom build. Each time I generate a tsconfig.json file on a new project, I forget to add the build options, and also forget the exact syntax :)
I'd like to add the defaults to tsconfig so me including others can clearly see it and switch to false without too much thinking.

"compileOnSave": true,
"buildOnSave": true,

For better usability. I'll send a PR soon if this sounds right.

Thanks, the plugin is amazing!