Add functions to get default primitives

[gsheni]

Pull Request Description

• Add get_default_aggregation_primitives and get_default_transform_primitives to primitives.utils
• Have DFS run these functions to get the default primitives. In addition, users can call these functions to get the list of primitives.
• Rename test file from test_list_primitives.py to test_primitives_utils.py since the file tests functions in the utils of primitives

[codecov]

Codecov Report

Merging #945 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #945   +/-   ##
=======================================
  Coverage   98.22%   98.22%           
=======================================
  Files         119      119           
  Lines       10859    10873   +14     
=======================================
+ Hits        10666    10680   +14     
  Misses        193      193           

Impacted Files	Coverage Δ
featuretools/primitives/api.py	100.00% <ø> (ø)
featuretools/primitives/utils.py	99.08% <100.00%> (+0.05%)	⬆️
featuretools/synthesis/deep_feature_synthesis.py	97.04% <100.00%> (ø)
...retools/tests/utils_tests/test_primitives_utils.py	100.00% <100.00%> (ø)

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[rwedge]

What do you think of adding these to the list of ft.primitives.utils functions callable from ft.primitives (currently get_aggregation_primitives, get_transformation_primitives, and list_primitives are like that)

[gsheni]

What do you think of adding these to the list of ft.primitives.utils functions callable from ft.primitives (currently get_aggregation_primitives, get_transformation_primitives, and list_primitives are like that)

Yep, sounds good. Added it to the api.py

[rwedge]

Looks good