[hid_bravura_monitor.winlog] Add ECS error.code mapping

[andrewkroh]

What does this PR do?

The winlog input can produce error.code under some conditions so make sure their is a mapping present for the field that is aligned to ECS.

Relates #6766

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

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Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

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• Start Time: 2023-07-07T12:44:20.493+0000

• Duration: 15 min 16 sec

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Passed	61
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Total	61

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (2/2)	💚
Files	100.0% (2/2)	💚
Classes	100.0% (2/2)	💚
Methods	92.0% (23/25)	👍 29.113
Lines	98.259% (508/517)	👎 -1.186
Conditionals	100.0% (0/0)	💚