* [Fix] be able to parse ids if numeric and non-numeric values are used together
* add required package info and cache note into docstring
* duplicate node id is not allowed
* [Feature] support non-numeric node_id/src_id/dst_id/graph_id and rename CSVDataset
* change return value when iterate dataset
* refine data_parser
* force reload
* [Feature] add CSVDataset to load data from csv files
* add CSVDataset class file
* install pyyaml when running unit tests
* install pandas for unit tests
* utilize pydantic for YAML config check
* generate yaml and csv files during test
* make more keys as optional
* remove/rename several keys in yaml config and more tets though looks a bit clumsy
* fix test failure on mxnet
* pass /path/to/dataset instead of yaml path
* code refinement
* code refine
* change several yaml field such as feat and graph_id
* merge graph generation logic
* refine code
* Refactored_first_version
* DGLCSVDataset works for single heterograph
* add more tests
* fix test failure in mxnet
* add docstring
* use list comprehension for dict
* fix version in YAML
* refine data length assert
* use dict.pop directly
* remove ambiguous variable names
* refine graph id missing logic
* refine graph create call
* separate node/edge/graph data parser
* remove separator in DefaultDataParser
* refine validation error log for yaml field
* minor check
* refine code via dict.get()
* move load_from_csv into Node/Edge/GraphData
* move _parse_node/edge/graph_data into Node/Edge/GraphData
* refine id-related fields check
* check duplicate ntypes/etypes when load yaml
* refine docstring
Hongzhi (Steve), Chen