Pass file object where it makes sense for announced interceptions

[grantcopley]

The file object was created after we added announced interceptions for various file operations.

For example, consider the cbfsOnFileCreate interception. The listener signature looks like this.

function cbfsOnFileCreate( path, contents, visibility, metadata, overwrite, mode, disk ) {

}

This can be greated simplified now that we have a file object that pass around.

function cbfsOnFileCreate( file ) {

}