create_fresh_base_sysimage(): Pass "" as the BUILDROOT for Julia 1.12+

[DilumAluthge]

Fixes #989.

This fixes the immediate bug in #989, which is that Base.jl incorrectly assumes that our first positional argument is the value of the BUILDROOT. The fix is to pass a second positional argument "", which is then taken by Base.jl to be the BUILDROOT.

This bugfix PR will eventually be followed up by #997, which is a larger PR that will actually take advantage of the new BuildSettings mechanism added to Julia 1.12 in JuliaLang/julia#54387

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.56%. Comparing base (38629b0) to head (6e15a4e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #996   +/-   ##
=======================================
  Coverage   84.56%   84.56%           
=======================================
  Files           3        3           
  Lines         823      823           
=======================================
  Hits          696      696           
  Misses        127      127           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[DilumAluthge]

I think that it's fine to just always pass this argument unconditionally, because AFAICT it will just be ignored on older Julia versions. But if we want, we could instead gate this behind an if VERSION >= v"1.12-".

[DilumAluthge]

Also, I went ahead and bumped the version number (from 2.1.22 to 2.1.23), so that we can tag a new release after we merge this PR.

I determined the bump as follows:

1. This PR is a bugfix PR.
2. There is currently only one commit on master since the last release, and that commit is a CI-only commit.

[DilumAluthge]

@KristofferC Any objection to moving forward with this PR as a bug fix (and then doing the more involved work in #997)?

[DilumAluthge]

Closing in favor of #1002.