Update functionality to download demos

[fealho]

CU-86b6fugf3, Resolve #2661
CU-86b6fugf3, Resolve #2663
CU-86b6xkdcf, Resolve #2686
CU-86b6xjuk7, Resolve #2685
CU-86b6xjugh, Resolve #2684
CU-86b6xrcb1, Resolve #2689
CU-86b6xrqf0, Resolve #2691
CU-86b6xnx26, Resolve #2687
CU-86b6xp7a0, Resolve #2688
CU-86b6xrcah, Resolve #2690

[sdv-team]

Task linked: CU-86b6fugf3 SDV - Add get_source and get_readme functions for demo datasets #2663
Task linked: CU-86b6xjugh SDV - If a source or readme does not exist for a dataset, show a warning #2684
Task linked: CU-86b6xjuk7 SDV - Ensure that the source/readme files can only be downloaded in txt format #2685
Task linked: CU-86b6xkdcf SDV - Prevent users from accidentally overriding the source or README files #2686
Task linked: CU-86b6xnx26 SDV - download_demo failing when output_folder_path is set #2687
Task linked: CU-86b6xp7a0 SDV - download_demo may fail for some data.zip files #2688
Task linked: CU-86b6xrcah SDV - download_demo should ignore non-csv files in data.zip #2690
Task linked: CU-86b6xrcb1 SDV - Improve error message when no csv file are found for a dataset when using download_demo #2689
Task linked: CU-86b6xrqf0 SDV - download_demo errors if the dataset_name in the metainfo does not match the dataset name in the folder #2691

[codecov]

Codecov Report

❌ Patch coverage is 96.57143% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.16%. Comparing base (0491064) to head (6ce265a).

Files with missing lines	Patch %	Lines
sdv/datasets/demo.py	96.53%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2705      +/-   ##
==========================================
- Coverage   98.18%   98.16%   -0.03%     
==========================================
  Files          74       74              
  Lines        7771     7896     +125     
==========================================
+ Hits         7630     7751     +121     
- Misses        141      145       +4     

Flag	Coverage Δ
integration	76.06% <77.71%> (-0.21%)	⬇️
unit	96.89% <92.00%> (-0.11%)	⬇️

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