feat: Add B-field accessors to Python bindings

[stephenswat]

As #3479 reveals, we don't currently have any clean, cache-aware ways of accessing B-fields in Python code. In order to avoid hacks, this commit adds the necessary bindings to allow us to cleanly access B-fields with cache objects.

[github-actions]

📊: Physics performance monitoring for 3fc962a

Full contents

physmon summary

• ✅ Particles fatras
• ✅ Particles geant4
• ✅ Particles ttbar
• ✅ Vertices ttbar
• ✅ Truth tracking (KF)
• ✅ Truth tracking (GSF)
• ✅ Truth tracking (GX2F)
• ✅ CKF | trackfinding | single muon | truth smeared seeding
• ✅ Track Summary CKF | trackfinding | single muon | truth smeared seeding
• ✅ Seeding trackfinding | single muon | truth estimated seeding
• ✅ CKF | trackfinding | single muon | truth estimated seeding
• ✅ Track Summary CKF | trackfinding | single muon | truth estimated seeding
• ✅ Seeding trackfinding | single muon | default seeding
• ✅ CKF | trackfinding | single muon | default seeding
• ✅ Track Summary CKF | trackfinding | single muon | default seeding
• ✅ Seeding trackfinding | single muon | orthogonal seeding
• ✅ CKF | trackfinding | single muon | orthogonal seeding
• ✅ Track Summary CKF | trackfinding | single muon | orthogonal seeding
• ✅ Seeding trackfinding | 4 muon x 50 vertices | default seeding
• ✅ CKF | trackfinding | 4 muon x 50 vertices | default seeding
• ✅ Track Summary CKF | trackfinding | 4 muon x 50 vertices | default seeding
• ✅ Ambisolver | trackfinding | 4 muon x 50 vertices | default seeding
• ✅ IVF notime | trackfinding | 4 muon x 50 vertices | default seeding
• ✅ AMVF gauss notime | trackfinding | 4 muon x 50 vertices | default seeding
• ✅ AMVF grid time | trackfinding | 4 muon x 50 vertices | default seeding
• ✅ Seeding trackfinding | ttbar with 200 pileup | default seeding
• ✅ CKF | trackfinding | ttbar with 200 pileup | default seeding
• ✅ Track Summary CKF | trackfinding | ttbar with 200 pileup | default seeding
• ✅ Ambisolver | trackfinding | ttbar with 200 pileup | default seeding
• ✅ AMVF gauss notime | trackfinding | ttbar with 200 pileup | default seeding
• ✅ AMVF grid time | trackfinding | ttbar with 200 pileup | default seeding

[paulgessinger]

I'm generally hesitant to add too much of the Core lib to python, but I prefer this over the alternative I think. So let's do it.

[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[acts-project-service]

🔴 Athena integration test results [a04b130]

🔴 Some tests have failed!

Please investigate the pipeline!

status	job	report
🟢	report_pull_request
🟢	run_art_test: test_data18_13TeV_1000evt
🟢	run_art_test: test_ttbarPU40_reco
🟢	test_ActsDumpGeometryIdentifiers
🔴	test_ActsCheckObjectCountsCachedWorkflow
🔴	test_ActsCheckObjectCountsWorkflow
🟢	test_ActsEFTrackFit
🟢	test_ActsPersistifySeeds
🟢	test_ActsBenchmarkWithSpot
🟢	test_ActsAnalogueClustering
🔴	test_ActsWorkflowHeavyIons
🔴	test_ActsWorkflowFastTracking
🔴	test_ActsWorkflowCached
🔴	test_ActsWorkflow
🟢	test_ActsValidateAmbiguityResolution
🔴	test_ActsValidateResolvedTracks
🟢	test_ActsValidateTracks
🟢	test_ActsValidateActsCoreSpacePoints
🟢	test_ActsValidateActsSpacePoints
🟢	test_ActsValidateSeeds
🟢	test_ActsValidateOrthogonalSeeds
🟢	test_ActsValidateClusters
🔴	test_ActsPersistifyEDM
🟢	test_ActsGSFRefitting
🟢	test_ActsKfRefitting
🟢	test_ActsExtrapolationAlgTest
🟢	test_ActsITkTest
🟢	run_workflow_tests_run4_mc
🟢	run_workflow_tests_run2_mc
🟢	run_workflow_tests_run2_data
🟢	run_workflow_tests_run3_mc
🟢	run_workflow_tests_run3_data
🟢	run_unit_tests