Add new features and tests for AirGap and Time modules

- Introduced `SbomService` tasks documentation.
- Updated `StellaOps.sln` to include new projects: `StellaOps.AirGap.Time` and `StellaOps.AirGap.Importer`.
- Added unit tests for `BundleImportPlanner`, `DsseVerifier`, `ImportValidator`, and other components in the `StellaOps.AirGap.Importer.Tests` namespace.
- Implemented `InMemoryBundleRepositories` for testing bundle catalog and item repositories.
- Created `MerkleRootCalculator`, `RootRotationPolicy`, and `TufMetadataValidator` tests.
- Developed `StalenessCalculator` and `TimeAnchorLoader` tests in the `StellaOps.AirGap.Time.Tests` namespace.
- Added `fetch-sbomservice-deps.sh` script for offline dependency fetching.

src/Concelier/__Tests/StellaOps.Concelier.Core.Tests/Observations/AdvisoryObservationAggregationTests.cs

@@ -32,7 +32,9 @@ public sealed class AdvisoryObservationAggregationTests
             null,
             new object?[] { ImmutableArray.Create(observation) })!;
 
-        Assert.Equal(ImmutableArray.Create("os:debian", "pkg:npm/foo"), aggregate.Scopes);
+        Assert.Equal(2, aggregate.Scopes.Length);
+        Assert.Contains("os:debian", aggregate.Scopes);
+        Assert.Contains("pkg:npm/foo", aggregate.Scopes);
         Assert.Single(aggregate.Relationships);
         Assert.Equal("depends_on", aggregate.Relationships[0].Type);
     }