[XAPI-1544] Centralise codegen script (#407)

* [XAPI-1544] Refactor docs generation scripts

* [XAPI-1544] Create shared script for codegen
And update all languages to use it

* [XAPI-1544] Update working directory

* [XAPI-1544] Remove options
Don't seem to be required, resulting code is the same without

* [XAPI-1544] Fix scripts

* [XAPI-1544] Move cleanup outside of accounting generation

* [XAPI-1544] Refactor to define each task once with parameters

* [XAPI-1544] Download specs once

* [XAPI-1544] Always clean output dir
Centralise logic

* [XAPI-1544] Add clearer messaging and debug flag

* [XAPI-1544] Show how many files were modified

* [XAPI-1544] Always set branch and repo

* [XAPI-1544] Remove validation
Overkill

Author: actions-user