[winlogbeat] lowercase and despace/dehyphen all field names before processing

[ash-darin]

Describe the problem

Windows logs fields with various diverging field names:

IPAddress
IpAddress
Ipaddress
ipAdress

Win32 Error
win32Error
Win32Error

Powershell-ID
PowershellID

are all real field names that result in separate fields in Elasticsearch.

Describe the enhancement:

lowercase all field names and remove spaces (" ") and hyphens ("-") befor processing them. This should significantly cut down on issues with duplicate fields that defy standardization.

Describe a specific use case for the enhancement or feature:
Be able to work with more uniform field names.

Describe drawbacks
This would be a breaking change that would need refactoring of user dashboards.

[botelastic]

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