Use asciidoc include instead of custom macros

[AndreaLaGrotteria]

In guides-core use asciidoc built-in include system instead of custom macros solution.

common

common:header-top.adoc[]

would become

include::{commonsDir}/common-header-top.adoc[]

external-template

external-template:micronaut-k8s-oci/k8s-microservice.adoc[arg0=users] would become

:arg0: users
include::{guidesDir}/micronaut-k8s-oci/k8s-microservice.adoc[]

for guides that were using the syntax {arg0:U} to make argument uppercase, the macro would become

:arg0: users
:arg0Upper: USERS
include::{guidesDir}/micronaut-k8s-oci/k8s-microservice.adoc[]

callout

callout:controller[number=1,arg0=/hello]
callout:get[number=2,arg0=index,arg1=/hello]
callout:text-plain[3]

would become

:arg0: hello
include::{calloutDir}/callout-controller[]
:arg0: index
:arg1: /hello
include::{calloutDir}/callout-get[]
include::{calloutDir}/callout-text-plain[]

the explicit numeration is not needed since asciidoc does that automatically.

We would need to update the guide asciidoc of the included files where {arg0:U} is present to replace it with {arg0Upper} and every callout, adding <.> at the begging of the line.

[AndreaLaGrotteria]

We can also keep the old macros and translate them before passing the file to asciidoctor. This would essentially be the same as what we do with the source:, which is just translated into an include (in contrast with common: which imports the file directly)

[sdelamo]

If you are willing to da PR which updates every guide to this, I am happy to accept it.