feat(tvix/repl): Add a command to recursively print

Add a command, :p, to evaluate an expression and recursively print the
result, as if `--strict` had been passed on the command line.

Demonstration of this working:

    ❯ cargo r --bin tvix
        Finished dev [unoptimized + debuginfo] target(s) in 0.27s
        Running `target/debug/tvix`
    tvix-repl> { x = (x: x) 1; }
    => { x = <CODE>; } :: set
    tvix-repl> :p { x = (x: x) 1; }
    => { x = 1; } :: set

Change-Id: I1a81d7481160c30d2a4483c6308e25fa45f2dfdf
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11738
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

tvix/cli/src/main.rs

@@ -18,7 +18,7 @@ use tvix_glue::tvix_io::TvixIO;
 use tvix_glue::tvix_store_io::TvixStoreIO;
 use tvix_glue::{builtins::add_derivation_builtins, configure_nix_path};
 
-#[derive(Parser)]
+#[derive(Parser, Clone)]
 struct Args {
     #[arg(long)]
     log_level: Option<Level>,