feat: Add timings subcommand (#1629)

* feat: Add computational duration to all computed modules

This also means that in case we do some computations and these end up empty, we submit an empty module

* feat: Add timings subcommand

This outputs the timings of all computed modules, sorted by the duration it took to compute the module.

Useful for debugging why the prompt takes so long.

* feat: Add timings to explain output

* fix: Ensure that even empty custom modules get timings

* format main.rs

* feat: Only show interesting timings

* fix(tests): Change tests to look for empty string instead of None

* Use proper wording in timings help

* Revert "fix(tests): Change tests to look for empty string instead of None"

This reverts commit aca5bd1b03.

* fix(tests): Returning None in case the module produced an empty string

* fix: Ensure that linebreaks (and space) make a module not-empty

* Make cargo clippy happy

* Make Module.duration a proper Duration

* Only return a module if we would report it

* Change to cleaner way to return None for empty modules

* Avoid unnecessary module creation

* Simplify a string comparison

* Add timings to trace

Co-authored-by: Thomas O'Donnell <andytom@users.noreply.github.com>

Co-authored-by: Thomas O'Donnell <andytom@users.noreply.github.com>

src/test/mod.rs

@@ -84,7 +84,12 @@ impl<'a> ModuleRenderer<'a> {
 
     /// Renders the module returning its output
     pub fn collect(self) -> Option<String> {
-        crate::print::get_module(self.name, self.context)
+        let ret = crate::print::get_module(self.name, self.context);
+        // all tests rely on the fact that an empty module produces None as output as the
+        // convention was that there would be no module but None. This is nowadays not anymore
+        // the case (to get durations for all modules). So here we make it so, that an empty
+        // module returns None in the tests...
+        ret.filter(|s| s != "")
     }
 }