Gate Kotlin and Go release publishes on env approvals

Wires the new `release-github-packages` and `release-go` environments
into the publish jobs so releases pause for approval before pushing
the Maven artifact (Kotlin) or the go/v* git tag (Go), matching the
existing gates on TypeScript (`release-npm`) and Ruby (`release-rubygems`).

Swift release is git-tag-only with no publish job, so there's nothing
meaningful to gate there — the SwiftPM artifact is the tag itself,
which exists before any workflow runs.

Author: jeremy

.github/workflows/release-go.yml

@@ -69,6 +69,7 @@ jobs:
     needs: [smithy, test]
     if: github.event_name == 'push'
     runs-on: ubuntu-latest
+    environment: release-go
     permissions:
       contents: write
     steps:

.github/workflows/release-kotlin.yml

@@ -46,6 +46,7 @@ jobs:
     name: Publish to GitHub Packages
     needs: [smithy, test]
     runs-on: ubuntu-latest
+    environment: release-github-packages
     permissions:
       contents: read
       packages: write