Miscellaneous enhancements for 2023-W07

[khaeru]

• .disutility.get_spec() preserves all SDMX Annotations attached to the Code object used as a template for usage technologies.
• New function .util.replace_par_data(), analogous to .util.add_par_data().
• Expand exports from .util.
• Add CO2_Emission_Global_Total to the "A" relations code list.

Housekeeping:

• Add pytest-xdist to "tests" optional dependencies.
• Use reusable workflows for lint, publish.
• "pytest" GHA workflow:
  • Use first-party concurrency: settings instead of 3rd-party styfle/cancel-workflow-action.
  • Use pytest-xdist to run tests in parallel and shorten job times.
  • Remove redundant "update pip" step.

How to review

Read the diff and note that the CI checks all pass.

PR checklist

• [x] Continuous integration checks all ✅
• [x] Add or expand tests; coverage checks both ✅
• [x] Add, expand, or update documentation.
• [x] Update doc/whatsnew.

[codecov[bot]]

Codecov Report

Merging #90 (52d6e23) into main (0c6fa02) will increase coverage by 0.26%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #90      +/-   ##
==========================================
+ Coverage   66.83%   67.09%   +0.26%     
==========================================
  Files          58       58              
  Lines        3977     4009      +32     
==========================================
+ Hits         2658     2690      +32     
  Misses       1319     1319              

Impacted Files	Coverage Δ
message_ix_models/tests/model/test_bare.py	100.00% <ø> (ø)
message_ix_models/util/_convert_units.py	100.00% <ø> (ø)
message_ix_models/model/bare.py	100.00% <100.00%> (ø)
message_ix_models/model/build.py	100.00% <100.00%> (ø)
message_ix_models/model/disutility.py	100.00% <100.00%> (ø)
message_ix_models/model/structure.py	100.00% <100.00%> (ø)
message_ix_models/model/water/utils.py	30.64% <100.00%> (ø)
message_ix_models/tests/model/test_disutility.py	100.00% <100.00%> (ø)
message_ix_models/tests/model/test_structure.py	100.00% <100.00%> (ø)
message_ix_models/tests/test_util.py	100.00% <100.00%> (ø)
... and 8 more