Add WebSocket proxy to integration test gateway [Reference PR - Do Not Merge]

[paskozdilar]

REFERENCE PR - DO NOT MERGE

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I'm trying to get Bazel to build and run my integration tests so I can verify they fail.

For the first step, I've added a WebSocket proxy to examples/internal/gateway/handlers.go, without any tests, but Bazel build fails on my machine:

ERROR: no such package '@@[unknown repo 'com_github_gorilla_websocket' requested from @@]//': The repository '@@[unknown repo 'com_github_gorilla_websocket' requested from @@]' could not be resolved: No repository visible as '@com_github_gorilla_websocket' from main repository. Was the repository introduced in WORKSPACE? The WORKSPACE file is disabled by default in Bazel 8 (late 2024) and will be removed in Bazel 9 (late 2025), please migrate to Bzlmod. See https://bazel.build/external/migration
ERROR: /grpc-gateway/examples/internal/gateway/BUILD.bazel:3:11: no such package '@@[unknown repo 'com_github_gorilla_websocket' requested from @@]//': The repository '@@[unknown repo 'com_github_gorilla_websocket' requested from @@]' could not be resolved: No repository visible as '@com_github_gorilla_websocket' from main repository. Was the repository introduced in WORKSPACE? The WORKSPACE file is disabled by default in Bazel 8 (late 2024) and will be removed in Bazel 9 (late 2025), please migrate to Bzlmod. See https://bazel.build/external/migration and referenced by '//examples/internal/gateway:gateway'
Use --verbose_failures to see the command lines of failed build steps.
ERROR: Analysis of target '//examples/internal/gateway:gateway' failed; build aborted: Analysis failed
INFO: Elapsed time: 5.309s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
ERROR: Build did NOT complete successfully
ERROR: No test targets were found, yet testing was requested
FAILED:
    Fetching repository @@gazelle++go_deps+org_golang_google_grpc; starting 5s
    Fetching repository @@gazelle++go_deps+org_golang_x_text; starting 5s
    Fetching repository @@gazelle++go_deps+org_golang_x_oauth2; starting 5s
    Fetching repository @@gazelle++go_deps+com_github_antihax_optional; starting 5s
    Fetching repository @@gazelle++go_deps+org_golang_google_genproto_googleapis_api; starting 5s
    Fetching repository @@gazelle++go_deps+org_golang_google_genproto_googleapis_rpc; starting 5s
    Fetching repository @@gazelle++go_deps+org_golang_google_grpc_cmd_protoc_gen_go_grpc; starting 5s
    Fetching repository @@googleapis+; starting 5s ... (10 fetches)

@johanbrandhorst
Do you have an idea what might be wrong here?