Add shared, lazy SessionKeySupplier implementation (#936)

During startup, prof shows that a significant time is spent inside RSA key generation in the default SessionKeySupplierImpl, both in the constructor and in refreshKeys. This PR adds a new implementation that avoids generating keys until first time of use, and shares the session key between authorization providers.

Sharing between bootstrap and normal context is not yet implemented.

I have no way to test this, so can't say how much it helps.

* fix(deps): update oci to v3.44.1 (#931)

.github/workflows/graalvm-oci.yml

@@ -96,7 +96,7 @@ jobs:
            GRADLE_ENTERPRISE_CACHE_PASSWORD: ${{ secrets.GRADLE_ENTERPRISE_CACHE_PASSWORD }}
            PREDICTIVE_TEST_SELECTION: "${{ github.event_name == 'pull_request' && 'true' || 'false' }}"
       - name: Add build scan URL as PR comment
-        uses: actions/github-script@v6
+        uses: actions/github-script@v7
         if: github.event_name == 'pull_request' && failure()
         with:
           github-token: ${{secrets.GITHUB_TOKEN}}