In preparation for packaging of tls_wolfssl, add an example script to create source tarball with submodule code.

#### Pre-Submission Checklist - [X ] Commit message has the format required by CONTRIBUTING guide - [X] Commits are split per component (core, individual modules, libs, utils, ...) - [X ] Each component has a single commit (if not, squash them into one commit) - [X] No commits to README files for modules (changes must be done to docbook files in `doc/` subfolder, the README file is autogenerated)

#### Type Of Change - [ ] Small bug fix (non-breaking change which fixes an issue) - [X] New feature (non-breaking change which adds new functionality) - [ ] Breaking change (fix or feature that would change existing functionality)

#### Checklist: - [ ] PR should be backported to stable branches - [X] Tested changes locally - [ ] Related to issue #XXXX (replace XXXX with an open issue number)

#### Description In preparation for packaging tls_wolfssl the distributed source tarballs need to have the submodule instantiated and tar'ed together with the primary source code. This is an example script to package submodule code with the main code.

It can be used in CI/CD to prepare the tarball.

Subsequently I will update the pkg/ scripts to enable packaging of tls_wolfssl. You can view, comment on, or merge this pull request online at:

https://github.com/kamailio/kamailio/pull/3590

-- Commit Summary --

* pkg: add example script to create tarball with submodules instantiated

-- File Changes --

A pkg/scripts/git-archive-all.sh (25)

-- Patch Links --

https://github.com/kamailio/kamailio/pull/3590.patch https://github.com/kamailio/kamailio/pull/3590.diff