Do not lower-case FQDN

[AndersonQ]

This PR reverts #180

Complying with ECS for host.name and host.hostname (https://www.elastic.co/guide/en/ecs/current/ecs-host.html#field-host-name) should not be handled by go-sysinfo. The users of go-sysinfo should ensure compliance with ECS if necessary.

Relates to elastic/beats#39993

[andrewkroh]

Suggested change

	```release-note:enhancement
	```release-note:breaking-change

I would consider this to be breaking.

[jlind23]

@AndersonQ while testing did you check that:

• host.hostname was left untouched
• host.name was lowercased

[AndersonQ]

@AndersonQ while testing did you check that:

• host.hostname was left untouched
• host.name was lowercased

Yes, I did:

[AndersonQ]

@andrewkroh do you think it's worth adding a flag to choose to have FQDN lower-cased or not?

[andrewkroh]

do you think it's worth adding a flag to choose to have FQDN lower-cased or not?

No, as long as this library is clear through godocs that it is leaving the value in its original format without any normalization. Going forward we'll keep the library unopinionated on hostname formats.

[andrewkroh]

Can you please specify the affected parts of the library. As a library consumer I would want to know that the value in types.HostInfo#Hostname and the response from FQDN()/FQDNWithContext() are affected. It makes it easier to audit if you are affected.

IMO we could entirely omit mentions of ECS. It would suffice to say that if you want to retain the old behavior that it is your responsibility to lowercase the values.