chore(BREAKING): node 18 (#948)

## 🧰 Changes

BREAKING CHANGE: Bumps the minimum required Node versions for all of our
Node packages.

By bumping to Node 18 (and therefore `npm@9`), we can also bump our NPM
lockfiles to `lockfileVersion@3` and remove a lot of duplicated
lockfiles in the process.

As part of this, our integration tests now `npm i` rather than `npm ci`
since there are no lockfiles in subdirectories for them to refer to.
This is probably an improvement in a way since this more closely matches
the dependency resolution approach our users would take.

## 🧬 QA & Testing

Does everything still pass?

.github/workflows/cloudflare-worker.yml

@@ -14,10 +14,9 @@ jobs:
         working-directory: packages/cloudflare-worker
 
     strategy:
+      fail-fast: false
       matrix:
         node-version:
-          - 14
-          - 16
           - 18
           - 20
 

.github/workflows/nodejs.yml

@@ -32,10 +32,9 @@ jobs:
         working-directory: packages/node
 
     strategy:
+      fail-fast: false
       matrix:
         node-version:
-          - 14
-          - 16
           - 18
           - 20
 

.github/workflows/snippets.yml

@@ -14,10 +14,9 @@ jobs:
         working-directory: packages/sdk-snippets
 
     strategy:
+      fail-fast: false
       matrix:
         node-version:
-          - 14
-          - 16
           - 18
           - 20