Add swa.json config file

Describe the solution you’d like As a user, I’d like to be able to start swa using a config file. All the CLI flags should be supported.

{
  "options": {
   // CLI flags
  }
}

File name options:

• swa.json
• swa.config.json
• .swarc
• swa property in package.json

[alexweininger]

I really like this feature. I’m exploring adding local debugging for SWAs into the VS Code extension and this would make the configuration much easier on users.

I think users would be much more comfortable editing a swa-cli.config.json versus launch/tasks.json files.

[itpropro]

• swa property in package.json could lead to problems with monorepos
• swa.json not really clear that it’s a config file
• swa.config.json, .swarc both fine for me

I would prefer .swarc, as I think the most important thing about the naming would be to avoid confusion with the staticwebapp.config.json file for the user.