feat: added commandline option to define config file name

[swollner]

We need to be able to use a slightly modified configuration in our CI/CD pipeline. Therefore, we added an option to define the configuration file name via command-line arguments / environment variables

[qoomon]

LGTM

[Copilot]

Pull Request Overview

Adds the ability to specify a custom configuration file name via a new command-line option or environment variable, falling back to the default <artifactId>.xml.

• Introduce versioning.configFile option and use it when initializing the config file.
• Fallback to <artifactId>.xml if no option is provided.
• Update README to document both command-line and environment-variable usage.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/main/java/me/qoomon/maven/gitversioning/GitVersioningModelProcessor.java	Added OPTION_CONFIG_FILE_NAME, new logic to pick config file name from CLI, fallback behavior
README.md	Documented VERSIONING_CONFIG_FILE env var and -Dversioning.configFile CLI flag

Comments suppressed due to low confidence (2)

src/main/java/me/qoomon/maven/gitversioning/GitVersioningModelProcessor.java:175

• New branch logic for default config file fallback isn't covered by existing tests; consider adding unit tests for both cases (with and without the versioning.configFile option).

        if(configFileName == null){

README.md:282

• README documents the environment variable VERSIONING_CONFIG_FILE but the code does not currently read this variable; update the documentation or implement support in code for this environment variable to ensure consistency.

  - `export VERSIONING_CONFIG_FILE=myConfig.xml`

[qoomon]

feel free to try version 9.11.0.

@swollner I'd be glad if you can confirm that it works as intended