Run slowest tests last and print status updates

[milesfrain]

Description of the change

When I first ran tests locally in this repo, my system stalled for a minute at 100% CPU, which made me think something was wrong. Not sure if this is a real problem, or if parsing is just really slow for the stack overflow tests.

This PR moves the slower stack overflow tests to the end of each suite and prints some status messages to users.

time spago test                                                       

Compiling Test.Main
           Src   Lib   All
Warnings   0     0     0  
Errors     0     0     0  
[info] Build succeeded.
Testing CodePoint parsing

Running basic tests
Running overflow tests (may take a while)


Testing CodeUnit parsing

Running basic tests
Running overflow tests (may take a while)
[info] Tests succeeded.

spago test  122.84s user 1.35s system 102% cpu 2:01.65 total

Also, wondering if we should configure actions to ignore readme files so updating the changlog doesn't unnecessarily re-trigger CI.

---

Checklist:

• Added the change to the changelog's "Unreleased" section with a link to this PR and your username

[milesfrain]

Don't think it's necessary to name authors in the changelog.

[milesfrain]

Oh, I didn't actually read the contrib template carefully enough in this case. Seems like there's a mismatch between core (no username) and contrib (with username).

• Core
• Contrib

I think no-username is easier.

[thomashoneyman]

We didn't used to associate any usernames with pull requests, but we'd like to going forward (for core, contrib, etc.). However, it is optional if you'd rather not have your username added.

[thomashoneyman]

I think it's a great idea to ignore readme files for actions.