feat(all): make @middy/core optional (#511)

* feat(tracer): moved middy as devDep + updated docs

* feat(tracer): simplified middy note in docs

* feat(metrics): moved middy as devDep + updated docs

* feat(logger): moved middy as devDep + updated docs

* chore(examples): bumped middy to latest 2.x

Author: dreamorosi

Diff for: docs/core/logger.md

@@ -119,10 +119,8 @@ Key | Example
 
 === "Middy Middleware"
 
-    !!! note
-        Middy comes bundled with Logger, so you can just import it when using the middleware.
-
     !!! tip "Using Middy for the first time?"
+        You can install Middy by running `npm i @middy/core`.
         Learn more about [its usage and lifecycle in the official Middy documentation](https://github.com/middyjs/middy#usage){target="_blank"}.
 
     ```typescript hl_lines="1-2 10-11"

Diff for: docs/core/metrics.md

@@ -208,10 +208,8 @@ You can add default dimensions to your metrics by passing them as parameters in
 
 === "Middy middleware"
 
-    !!! note
-        Middy comes bundled with Metrics, so you can just import it when using the middleware.
-
     !!! tip "Using Middy for the first time?"
+        You can install Middy by running `npm i @middy/core`.
         Learn more about [its usage and lifecycle in the official Middy documentation](https://github.com/middyjs/middy#usage){target="_blank"}.
 
     ```typescript hl_lines="1-2 11 13"

Diff for: docs/core/tracer.md

@@ -119,10 +119,8 @@ You can quickly start by importing the `Tracer` class, initialize it outside the
 
 === "Middy Middleware"
 
-    !!! note
-        Middy comes bundled with Tracer, so you can just import it when using the middleware.
-
     !!! tip "Using Middy for the first time?"
+        You can install Middy by running `npm i @middy/core`.
         Learn more about [its usage and lifecycle in the official Middy documentation](https://github.com/middyjs/middy#usage){target="_blank"}.
 
     ```typescript hl_lines="1-2 11 13"