Add code coverage report and moved scripts outside of src

[karan6181]

Description of changes:

• Add a code coverage report as part of pytest github action. This will help to improve the test coverage.
• The test coverage threshold kept as 50% for now. We need to improve the coverage in future and increase the threshold.
• Moved the standalone compression and hashing script out from streaming src folder.

Coverage report

---------- coverage: platform linux, python 3.9.15-final-0 -----------
Name                                        Stmts   Miss Branch BrPart     Cover   Missing
------------------------------------------------------------------------------------------
streaming/__init__.py                           6      0      0      0   100.00%
streaming/_version.py                           2      0      0      0   100.00%
streaming/base/__init__.py                      5      0      0      0   100.00%
streaming/base/compression/__init__.py          3      0      0      0   100.00%
streaming/base/compression/compression.py     104      5     16      4    92.50%   195, 236, 238, 254, 256
streaming/base/dataset.py                     263     25    108     20    86.25%   110->112, 184->187, 230, 236->exit, 240, 271->275, 273-274, 287-288, 318->322, 324, 349, 406->416, 410, 422->exit, 425-426, 458-463, 475->473, 482, 487, 520-523, 568-569, 577->580
streaming/base/distributed.py                  23      8      6      0    51.72%   63-72
streaming/base/download.py                     87     51     34      7    38.84%   25-39, 52-94, 126, 129, 131, 144-150, 173->184, 176, 182-183, 185
streaming/base/format/__init__.py              12      0      0      0   100.00%
streaming/base/format/base/__init__.py          1      0      0      0   100.00%
streaming/base/format/base/reader.py           46      3      4      0    90.00%   64, 108-109
streaming/base/format/base/writer.py          128      2     20      3    96.62%   59, 74, 211->214
streaming/base/format/json/__init__.py          4      0      0      0   100.00%
streaming/base/format/json/encodings.py        26      1      0      0    96.15%   50
streaming/base/format/json/reader.py           42     13      2      0    70.45%   92-93, 104-114
streaming/base/format/json/writer.py           36      0      4      0   100.00%
streaming/base/format/mds/__init__.py           4      0      0      0   100.00%
streaming/base/format/mds/encodings.py         88     26      2      1    70.00%   54, 57, 89-93, 96-102, 114-115, 122-124, 127-128, 138, 145, 148, 170, 196
streaming/base/format/mds/reader.py            53      0      8      0   100.00%
streaming/base/format/mds/writer.py            53      0      6      0   100.00%
streaming/base/format/xsv/__init__.py           4      0      0      0   100.00%
streaming/base/format/xsv/encodings.py         44      7      0      0    84.09%   52, 65, 73-74, 78, 120-121
streaming/base/format/xsv/reader.py            83     18      8      0    78.02%   97-103, 114-124
streaming/base/format/xsv/writer.py            68      0      4      0   100.00%
streaming/base/hashing/__init__.py              3      0      0      0   100.00%
streaming/base/hashing/hashing.py              24      2      8      1    90.62%   40, 66
streaming/base/index.py                        98     12     26      6    82.26%   64, 154-155, 181-184, 212-214, 216, 233
streaming/base/local.py                        28     16      4      0    37.50%   27-42, 50, 61-63
streaming/base/util.py                          5      5      0      0     0.00%   4-20
streaming/text/__init__.py                      4      0      0      0   100.00%
streaming/text/c4.py                           29     20      6      0    25.71%   61-74, 82-90, 104-107
streaming/text/convert/__init__.py              1      1      0      0     0.00%   4
streaming/text/convert/c4.py                   60     60     18      0     0.00%   4-154
streaming/text/convert/enwiki.py               41     41     12      0     0.00%   4-120
streaming/text/convert/enwiki/__init__.py       0      0      0      0   100.00%
streaming/text/enwiki.py                       18     10      2      0    40.00%   50-52, 74-84
streaming/vision/__init__.py                    6      0      0      0   100.00%
streaming/vision/ade20k.py                     21     14      6      0    25.93%   55-59, 70-79
streaming/vision/base.py                       37     23      8      0    31.11%   27-28, 40-46, 93-106, 117-120, 164
streaming/vision/cifar10.py                     4      0      0      0   100.00%
streaming/vision/coco.py                       19     12      2      0    33.33%   55-58, 69-80
streaming/vision/convert/__init__.py            1      1      0      0     0.00%   4
streaming/vision/convert/ade20k.py             58     58     26      0     0.00%   4-166
streaming/vision/convert/base.py               19     19      4      0     0.00%   4-55
streaming/vision/convert/cifar10.py            24     24      4      0     0.00%   4-88
streaming/vision/convert/coco.py              110    110     32      0     0.00%   4-244
streaming/vision/convert/imagenet.py           66     66     18      0     0.00%   4-164
streaming/vision/imagenet.py                    4      0      0      0   100.00%
------------------------------------------------------------------------------------------
TOTAL                                        1865    653    398     42    61.42%

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