Fixes #1522, add render-dependencies mojo

[rmannibucau]

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[slawekjaranowski]

We need a documentation with describe template context items and with example how to use it.

all parameters should have documentation with since tag

[slawekjaranowski]

also please fix

[INFO] --- dependency:3.8.1:analyze-only (analyze) @ maven-dependency-plugin --- [WARNING] Used undeclared dependencies found: [WARNING] org.apache.velocity.tools:velocity-tools-generic:jar:3.1:compile [WARNING] org.apache.velocity:velocity-engine-core:jar:2.4:compile 

[slawekjaranowski]

Please also add link to example to site.xml

[github-actions]

@rmannibucau Please assign appropriate label to PR according to the type of change.