Update SDK to use shared tooling for changelog and release handling

Updates the SDK to use shared tooling with the smithy-go repo for
handling changelogs and module releases.

Remove internal tooling that's been moved to shared repotools project.

.changelog/27fb280ebf754001a8194e392169c032.json

@@ -0,0 +1,8 @@
+{
+    "id": "27fb280e-bf75-4001-a819-4e392169c032",
+    "type": "bugfix",
+    "description": "Move internal changelog and release tooling into shared repository.",
+    "modules": [
+        "internal/repotools"
+    ]
+}

Makefile

@@ -19,7 +19,7 @@ EACHMODULE_SKIP_FLAG=-skip="${EACHMODULE_SKIP}"
 
 EACHMODULE_FLAGS=${EACHMODULE_CONCURRENCY_FLAG} ${EACHMODULE_FAILFAST_FLAG} ${EACHMODULE_SKIP_FLAG}
 
-# SDK's Core and client packages that are compatable with Go 1.9+.
+# SDK's Core and client packages that are compatible with Go 1.9+.
 SDK_CORE_PKGS=./aws/... ./internal/...
 SDK_CLIENT_PKGS=./service/...
 SDK_COMPA_PKGS=${SDK_CORE_PKGS} ${SDK_CLIENT_PKGS}
@@ -41,6 +41,15 @@ LICENSE_FILE=$(shell pwd)/LICENSE.txt
 RELEASE_MANIFEST_FILE ?=
 RELEASE_CHGLOG_DESC_FILE ?=
 
+REPOTOOLS_VERSION ?= latest
+REPOTOOLS_MODULE = github.com/awslabs/aws-go-multi-module-repository-tools
+REPOTOOLS_CMD_CALCULATE_RELEASE = ${REPOTOOLS_MODULE}/cmd/calculaterelease@${REPOTOOLS_VERSION}
+REPOTOOLS_CMD_UPDATE_REQUIRES = ${REPOTOOLS_MODULE}/cmd/updaterequires@${REPOTOOLS_VERSION}
+REPOTOOLS_CMD_UPDATE_MODULE_METADATA = ${REPOTOOLS_MODULE}/cmd/updatemodulemeta@${REPOTOOLS_VERSION}
+REPOTOOLS_CMD_GENERATE_CHANGELOG = ${REPOTOOLS_MODULE}/cmd/generatechangelog@${REPOTOOLS_VERSION}
+REPOTOOLS_CMD_CHANGELOG = ${REPOTOOLS_MODULE}/cmd/changelog@${REPOTOOLS_VERSION}
+REPOTOOLS_CMD_TAG_RELEASE = ${REPOTOOLS_MODULE}/cmd/tagrelease@${REPOTOOLS_VERSION}
+
 .PHONY: all
 all: generate unit
 
@@ -382,34 +391,31 @@ bench-modules-%:
 .PHONY: preview-release pre-release-validation release
 
 preview-release:
-	@cd ./internal/repotools && \
-		go run ./cmd/calculaterelease
+	go run ${REPOTOOLS_CMD_CALCULATE_RELEASE}
 
 pre-release-validation:
 	@if [[ -z "${RELEASE_MANIFEST_FILE}" ]]; then \
-      		echo "RELEASE_MANIFEST_FILE is required to specify the file to write the release manifest" && false; \
-      	fi
+		echo "RELEASE_MANIFEST_FILE is required to specify the file to write the release manifest" && false; \
+	fi
 	@if [[ -z "${RELEASE_CHGLOG_DESC_FILE}" ]]; then \
 		echo "RELEASE_CHGLOG_DESC_FILE is required to specify the file to write the release notes" && false; \
 	fi
 
 release: pre-release-validation
-	cd ./internal/repotools && \
-		go run ./cmd/calculaterelease -o ${RELEASE_MANIFEST_FILE} && \
-		go run ./cmd/updaterequires -release ${RELEASE_MANIFEST_FILE} && \
-		go run ./cmd/updatemodulemeta -release ${RELEASE_MANIFEST_FILE} && \
-		go run ./cmd/generatechangelog -release ${RELEASE_MANIFEST_FILE} -o ${RELEASE_CHGLOG_DESC_FILE} && \
-		go run ./cmd/changelog rm -all && \
-		go run ./cmd/tagrelease -release ${RELEASE_MANIFEST_FILE}
+	go run ${REPOTOOLS_CMD_CALCULATE_RELEASE} -o ${RELEASE_MANIFEST_FILE}
+	go run ${REPOTOOLS_CMD_UPDATE_REQUIRES} -release ${RELEASE_MANIFEST_FILE}
+	go run ${REPOTOOLS_CMD_UPDATE_MODULE_METADATA} -release ${RELEASE_MANIFEST_FILE}
+	go run ${REPOTOOLS_CMD_GENERATE_CHANGELOG} -release ${RELEASE_MANIFEST_FILE} -o ${RELEASE_CHGLOG_DESC_FILE}
+	go run ${REPOTOOLS_CMD_CHANGELOG} rm -all
+	go run ${REPOTOOLS_CMD_TAG_RELEASE} -release ${RELEASE_MANIFEST_FILE}
 
 ##############
 # Repo Tools #
 ##############
 .PHONY: install-repotools
 
 install-repotools:
-	cd ./internal/repotools && \
-		go install ./cmd/changelog
+	go install ${REPOTOOLS_MODULE}/cmd/changelog@${REPOTOOLS_VERSION}
 
 ##################
 # Linting/Verify #