SE-0257: Eliding commas from multiline expression lists

I want to point out that the package manager DSL was designed without this proposal in mind. It may be possible to design it differently if supporting comma elision was a goal. If Enhanced Variadic Parameters moves forward labeled variadic parameters may also be useful.

For example, it might be possible to re-skin it so:

package = Package(
    name: "Paper"
    products: [
        .executable(name: "tool", targets: ["tool"])
        .library(name: "Paper", targets: ["Paper"])

becomes:

package = Package(
    name: "Paper"
    products: [
        tool: .executable(targets: ["tool"])
        Paper: .library(targets: ["Paper"])