v3: Implicit firstUpper for private interfaces

[avorima]

Generating mocks for an unexported interface in v3 using

type myInterface interface {
        Something() error
}

dir: "{{.InterfaceDir}}"
pkgname: "{{.SrcPackageName}}"
structname: "{{.Mock}}{{.InterfaceName}}"
filename: "mock_{{.InterfaceName | snakecase}}_test.go"

yields this mock mockmyInterface, but it would be nice if it could be mockMyInterface without having to use {{.InterfaceName | firstUpper }}.
I might be imagining things, but I think this used to be the behavior in one of the previous mockery versions.

[LandonTClipp]

{{.InterfaceName | firstUpper }} is probably the right way to do this. We could add a new parameter that has this implicit behavior but I'm not sure what the real issue is with firstUpper, it works well enough no?