Standardized gremlin-go connection options

[GumpacG]

Standardize gremlin-go connection options

Implements the Go portion of the TinkerPop 4.x GLV connection-options standardization. Renames several settings fields to canonical names, moves the authentication helpers into a dedicated auth sub-package (flat functions kept as deprecated delegators), aligns defaults, adds new options, and fixes a silent proxy drop. Go driver changes only; the other GLVs follow in separate PRs.

Proposal: https://lists.apache.org/thread/yqtr2wnb1kq2pqqq4002cz511q5o0bkg

Renames (breaking)

Struct fields cannot be aliased, so these are hard renames and existing code must be updated.

Old	New	Default
MaximumConcurrentConnections	MaxConnections	128
IdleConnectionTimeout	IdleTimeout	180s
KeepAliveInterval	KeepAliveTime	30s
ConnectionTimeout	ConnectTimeout	5s
TlsConfig (*tls.Config)	Ssl	-
RequestInterceptors	Interceptors	-
EnableCompression	Compression	-

Auth helpers moved out of package gremlingo into a new auth sub-package (github.com/apache/tinkerpop/gremlin-go/v4/driver/auth):

Old	New
BasicAuth	auth.Basic
SigV4Auth	auth.SigV4
SigV4AuthWithCredentials	auth.SigV4WithCredentials

The flat gremlingo auth functions are retained as deprecated delegators (idiomatic Go // Deprecated: doc comments) so existing code keeps compiling. New code should use the auth sub-package.

Behavior changes (breaking)

• Compression is now a typed Compression const (gremlingo.CompressionNone/gremlingo.CompressionDeflate) and defaults to CompressionDeflate (on); the driver sends Accept-Encoding: deflate by default. Set gremlingo.CompressionNone to disable. The manual per-chunk deflate decode path is retained.
• http.Transport.Proxy now defaults to http.ProxyFromEnvironment, so HTTP_PROXY/HTTPS_PROXY/NO_PROXY are honored. The custom transport previously left Proxy unset, silently dropping any environment proxy configuration.

New options

• ReadTimeout (default 0, off) - a per-read idle timeout reset on each read of the response body and re-armed across pooled-connection reuse, so it never fires while a pooled connection is idle between requests.
• MaxResponseHeaderBytes - exposes http.Transport.MaxResponseHeaderBytes (native bytes).
• Proxy - an explicit proxy override for the transport.
• DefaultBatchSize (64) - connection-level default that fills a request's batchSize when unset.

The Go-specific MaxIdleConnections (count-based idle keep-alive cap, default 8) is unchanged.

Removed (breaking)

• MaxResponseContentLength - responses now stream; ReadTimeout is the partial mitigation.

Testing

• gremlin-go go build ./... and go vet ./... pass.
• Unit tests pass, including the relocated auth tests: auth.TestBasic/auth.TestSigV4 in the new auth sub-package, and TestDeprecatedBasicAuth/TestDeprecatedSigV4Auth covering the deprecated delegators.
• CHANGELOG, reference config table (gremlin-variants.asciidoc), and upgrade guide (release-4.x.x.asciidoc) updated for the Go slice.

Assisted-by: Kiro: Claude Opus 4.8

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.10%. Comparing base (a28cd1f) to head (b48aa07).
⚠️ Report is 150 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3467      +/-   ##
============================================
- Coverage     76.35%   76.10%   -0.26%     
- Complexity    13424    13646     +222     
============================================
  Files          1012     1026      +14     
  Lines         60341    61743    +1402     
  Branches       7075     7209     +134     
============================================
+ Hits          46076    46989     +913     
- Misses        11548    11869     +321     
- Partials       2717     2885     +168     

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[kenhuuu]

This PR has some open questions that are the same as the ones I mentioned in the PRs for the other GLVs. Other than those this LGTM.

[kenhuuu]

VOTE +1

[Cole-Greer]

VOTE +1

[xiazcy]

VOTE +1