[Feat] Implement GraphAr Spark Reader for reading GAR format files into Spark DataFrame

[acezen]

Is your feature request related to a problem? Please describe.
Implement the Spark Reader to provide functions for reading GraphAr files into Spark DataFrames.

Describe the solution you'd like
The reader should include VertexReader and EdgeReader:

• VertexReader provide functions to read a type of vertices at a time and assembles the result into the Spark DataFrames.
• EdgeReader provide functions to read edge chunks including adjList, offset and property chunks.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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