Add warning messages to magefile for version mismatches in beats

[fearful-symmetry]

What does this PR do?

This adds a few warning lines to the magefile to handle cases where there's a version mismatch between the agent repo and the beat repo. Shot myself in the foot a few times with this, so it will just quit if it detects a version mismatch.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[mergify]

This pull request does not have a backport label. Could you fix it @fearful-symmetry? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 8./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elasticmachine]

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• Start Time: 2023-10-13T19:22:02.174+0000

• Duration: 26 min 2 sec

Test stats 🧪

Test	Results
Failed	0
Passed	6493
Skipped	59
Total	6552

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	98.78% (81/82)	👍
Files	67.559% (202/299)	👍
Classes	66.187% (368/556)	👍
Methods	53.613% (1165/2173)	👍
Lines	39.738% (13545/34086)	👎 -0.038
Conditionals	100.0% (0/0)	💚

[belimawr]

LGTM, however I would make that an error and interrupt the packaging process.

I've shoot myself in the foot because of this as well. If we need mismatched versions for testing/development, we know what we're doing and we can just modify the version files.

As a general behaviour I rather error on the safe side and not generate an inconsistent package.

[ycombinator]

A few minor comments but overall LGTM!

[elastic-sonarqube]

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