Script to install elastic agent

[enggnr]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...) This PR provides a script that conditionally enrolls elastic agent with Elastic fleet server

• What is the current behavior? (You can also link to an open issue here) Elastic agent is not automatically enrolled

• What is the new behavior (if this is a feature change)? Fixes #26

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Files not summarized due to errors (2)

### Failed to summarize * home/.chezmoi.yaml.tmpl (nothing obtained from openai) * home/.chezmoiscripts/universal/run_onchange_after_57-elastic-agent.sh.tmpl (nothing obtained from openai)

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In the recent run, only the files that changed from the base of the PR and between 2dfb30a3b8eb3da1335bc095df468fca9934c8a8 and 06c0429dc596cfc40db8f5062080cb8051dcac96 commits were reviewed.

Files not reviewed due to errors in the recent run (2)

### Failed to review in the last run * home/.chezmoi.yaml.tmpl (no response) * home/.chezmoiscripts/universal/run_onchange_after_57-elastic-agent.sh.tmpl (no response)