Unify environment creation

[SarthakJariwala]

create command can now create new environments for the following 3 conditions:

New environment from scratch

$ ezconda create --name env

From environment specifications file (yml file)

$ ezconda create --file env.yml

From environment lock file

$ ezconda create --file env-darwin-x86_64.lock

This PR also deprecates recreate command for removal in v0.8.0

Appropriate doc changes were also made to reflect the new changes.

Closes #32

[codecov-commenter]

Codecov Report

Merging #34 (7c6ce42) into main (0df4681) will increase coverage by 0.28%.
The diff coverage is 85.00%.

❗ Current head 7c6ce42 differs from pull request most recent head 7b97950. Consider uploading reports for the commit 7b97950 to get more accurate results

@@            Coverage Diff             @@
##             main      #34      +/-   ##
==========================================
+ Coverage   91.03%   91.32%   +0.28%     
==========================================
  Files          16       16              
  Lines         502      507       +5     
==========================================
+ Hits          457      463       +6     
+ Misses         45       44       -1     

Impacted Files	Coverage Δ
ezconda/create.py	88.13% <83.33%> (+2.42%)	⬆️
ezconda/recreate.py	91.66% <100.00%> (+0.49%)	⬆️

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