Support multiple namespaces in the Nomad Provider

.golangci.yml

docs/content/deprecation/features.md

docs/content/migration/v2.md

docs/content/providers/nomad.md

docs/content/reference/static-configuration/cli-ref.md

docs/content/reference/static-configuration/env-ref.md

docs/content/reference/static-configuration/file.toml

docs/content/reference/static-configuration/file.yaml

docs/content/routing/providers/kubernetes-gateway.md

pkg/config/dynamic/fixtures/sample.toml

pkg/config/static/static_config.go

pkg/provider/aggregator/aggregator.go

pkg/provider/nomad/config_test.go

pkg/provider/nomad/nomad.go

pkg/provider/nomad/nomad_test.go

webui/src/components/_commons/PanelMiddlewares.vue

webui/src/components/_commons/PanelMirroringServices.vue

webui/src/components/_commons/PanelRouterDetails.vue

webui/src/components/_commons/PanelServiceDetails.vue

webui/src/components/_commons/PanelWeightedServices.vue