v1.48.0
cmake: update .gitignore files
Remove remaining SPDY code from the integration tests.
Run nghttpx integration test with cmake build
nghttpx: Refactor code to build cert_tree, add SNI test
integration-tests: support out-of-tree tests
Refactor serverTester constructor
Rearrange imports
nghttpx: Change mruby script handling
integration: Add TLS key and certificate for testing
Build with GitHub Actions