support pipeline analyzer

[muhammad-davatgar]

arangors currently doesn't support creating pipeline analyzers. which are very useful and would be nice to have
i have already implemented it in my own fork so ill just open a pull request. ill give a little explanation about what i have done below. it's my first contribution so i don't know where else i can put it. hope that's ok.

[muhammad-davatgar]

i added a new variant to AnalyzerInfo named Pipeline and which takes PipelineAnalyzerPropertiesas its property.
PipelineAnalyzerProperties has a file pipeline which is vector of PipelineAnalyzers. i had to copy AnalyzerInfo and delete name field because pipeline analyzers don't have name field in their sub-analyzers . and sending one(although it still creates the analyzer) results in a 400 response.
you can also run cargo test test_create_and_drop_pipeline_analyzer to test the added feature