[confignet] Should TransportType unmarshal be case insensitive?

[TylerHelmuth]

Is your feature request related to a problem? Please describe.
Came across a situation in Contrib where the TransportType could not be used because the exporter supported tcp or TCP, but the TransportType unmarshal expects lowercase only.

open-telemetry/opentelemetry-collector-contrib#32379 (comment)

Describe the solution you'd like
Should we consider treating the strings we're unmarshalling as case insensitive?

[mx-psi]

We can do this after 1.0, right? As long as the error message is clear, I don't think there is a need to do this right now

[TylerHelmuth]

I think it could wait until after 1.0 according to our version controls:

Relaxing validation rules. An invalid configuration struct as defined by its Validate method return value may become valid after a change to the validation rules.

[mx-psi]

Oki, I am going to remove from the 1.0 milestone then (we can still do it now, just want to make it clear this is not a blocker for 1.0)