Mark build output "sideEffects": false (#23501)

## Description

During the build we copy package.json files into the output for CJS
builds and some ESM builds. Thes files lacked `"sideEffects": false`
resulting in poor tree shaking for any bundle using build output with a
copied package.json. This included the tree package ESM build which
caused its bundle to bloat.

This package.json copy has been removed from the tree package's esm
build, but also update to include `"sideEffects": false` for builds that
use it.

common/build/build-common/src/cjs/package.json

@@ -1,3 +1,4 @@
 {
-	"type": "commonjs"
+	"type": "commonjs",
+	"sideEffects": false
 }

common/build/build-common/src/esm/package.json

@@ -1,3 +1,4 @@
 {
-	"type": "module"
+	"type": "module",
+	"sideEffects": false
 }

packages/dds/tree/package.json

@@ -79,7 +79,7 @@
 		"build:commonjs": "fluid-build . --task commonjs",
 		"build:compile": "fluid-build . --task compile",
 		"build:docs": "api-extractor run --local",
-		"build:esnext": "tsc --project ./tsconfig.json && copyfiles -f ../../../common/build/build-common/src/esm/package.json ./lib",
+		"build:esnext": "tsc --project ./tsconfig.json",
 		"build:genver": "gen-version",
 		"build:test": "npm run build:test:esm && npm run build:test:cjs",
 		"build:test:cjs": "fluid-tsc commonjs --project ./src/test/tsconfig.cjs.json",