Add optional inline project edit button

[farlee2121]

Motivation

A continuation of #269 which opened the project file on click in the explorer like Visual Studio does. The other popular F# editor is Ionide, which instead offers an inline button to edit the project file.

Supporting similar behavior could ease transition. It's also just a nice balanced option for quick access and a larger expand/collapse target.

Behavior after PR

By default there will be an inline button to edit the project file. This can be turned off in the settings.

Decisions worth noting

Config naming

The configuration option is "Open Project Inline Button Shown". This is less direct than "Show Inline Edit Project Button".
But, I chose it because it puts the two open project options right next to each other.

Alternatively, we could make the behaviors one configuration option with an enum.
I chose not to do that since it's plausible someone might want to toggle both.
Plus, I think only boolean config settings can be accessed directly from when constraints

Icon

I chose the edit icon for opening the project since it seemed intuitive. But VS Code has other sensible built-in icons like

• file-code
• go-to-file
• arrow-right

[fernandoescolar]

Amazing, thanks!