Adding bash-script for lightweight installs

[VIGNESHinZONE]

Pull Request Template

Description

Fix #2611 (Partially)

In this PR, I have included a shell script that installs deepchem package for them depending on the environment. Recommended only for Linux environments.

This is a Nightly install and was adapted from -

1. deepchem/docker/nightly/Dockerfile
2. [deepchem/scripts/install_deepchem_conda.sh]https://github.com/deepchem/deepchem/blob/master/scripts/install_deepchem_conda.sh)

source scripts/light/install_deepchem.sh 3.8 gpu tensorflow

[VIGNESHinZONE]

@rbharath I can update the above changes in

1. https://deepchem.readthedocs.io/en/latest/get_started/installation.html#from-source-with-conda
2. Nightly/Dockerfile

[codecov-commenter]

Codecov Report

Merging #2618 (87f27e1) into master (d636878) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2618      +/-   ##
==========================================
- Coverage   53.87%   53.85%   -0.02%     
==========================================
  Files         321      321              
  Lines       28548    28556       +8     
==========================================
  Hits        15379    15379              
- Misses      13169    13177       +8     

Impacted Files	Coverage Δ
deepchem/molnet/load_function/uspto_datasets.py	35.29% <0.00%> (-6.57%)	⬇️

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[rbharath]

Looks like some build errors have cropped up. Let me know once the errors are fixed and will do a pass!

[rbharath]

@VIGNESHinZONE Looks good to me. Let me know once CI is clear and this is ready to merge in!