Add OpenAPI specification for Link-Not-Merge Policy APIs

- Introduced a new OpenAPI YAML file for the StellaOps Concelier service.
- Defined endpoints for listing linksets, retrieving linksets by advisory ID, and searching linksets.
- Included detailed parameter specifications and response schemas for each endpoint.
- Established components for reusable parameters and schemas, enhancing API documentation clarity.

src/Provenance/StellaOps.Provenance.Attestation.Tool/StellaOps.Provenance.Attestation.Tool.csproj

@@ -4,6 +4,7 @@
     <LangVersion>preview</LangVersion>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
+    <OutputType>Exe</OutputType>
     <PackAsTool>true</PackAsTool>
     <ToolCommandName>stella-forensic-verify</ToolCommandName>
     <PackageOutputPath>../../out/tools</PackageOutputPath>