Support for actions mods in the development server

[handerss-spotfire]

The development server will require some minor changes to support action mods.

• Action mods will contain script files which are defined outside of the "files" section in the manifest. These files will be defined under the "scripts" property which will host and array of objects where each object specifies a file path via the "file" property. These files should be allowed to be fetched from the development server.
• There needs to be an endpoint where the absolute path of the project root can be retrieved. This is necessary since V8 requires an absolute path to the script file being execute to support source maps. In this PR this endpoint is only enabled when providing the "--allow-project-root true" argument. I'm not sure if we need to put it behind a flag though, I mainly did it to avoid "breaking" the API since someone hay have had a file named modProjectRoot.

[objerke]

I think adding a flag as proposed here is the best approach. It will make it more clear that this behavior is included, compared to other dev servers.

An alternative and less good solution is to add a more unique path with with less chance of a collision.

[handerss-spotfire]

Since we do not allow the path to start with "spotfire/" I could change it to something like that which won't break existing mods.

[objerke]

Since we do not allow the path to start with "spotfire/" I could change it to something like that which won't break existing mods.

I think that sounds like a good idea!

[handerss-spotfire]

The endpoint is now under the /spotfire path and the flag remains.

[ebrandin]

Looks good!

[hjockert]

👍