docs(maintenance): update Middy sections

[dreamorosi]

Description of your changes

Following internal feedback, this PR addresses the concerns described in the linked issue as well as two other docs-related issues.

Middy

The callouts related to Middy in the docs have been updated to clarify that Powertools supports only Middy v3.x (current latest being v4.x). In doing so I updated also the command to install the correct version as well as linking to the new section of the Middy docs dedicated to Powertools.

Tracer

The code snippets related to patching/capturing AWS SDK clients have been updated to show a more realistic example of usage. Prior to this change the examples were only showing the capture action but were not explaining how to use the patched client.

Now the snippets use a variable to store the patched client and show how to export the patched client in a way that allows usage in other modules.

General

The PR also reintroduces the MKDocs feature that allows to copy/paste code snippets which was mistakenly removed.

Related issues, RFCs

Issue number: #1523

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my change is effective and works
• The PR title follows the conventional commit semantics

Breaking change checklist

Is it a breaking change?: NO

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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