support for .env files in okteto up

[rberrelleza]

Proposed changes

• Read an available .env file on start, and inject the values to the environment for the rest of the commands

[codecov]

Codecov Report

Merging #1360 (ef4fc72) into master (b64902f) will decrease coverage by 0.15%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1360      +/-   ##
==========================================
- Coverage   36.24%   36.08%   -0.16%     
==========================================
  Files          79       80       +1     
  Lines        7261     7293      +32     
==========================================
  Hits         2632     2632              
- Misses       4301     4333      +32     
  Partials      328      328              

Impacted Files	Coverage Δ
cmd/up/up.go	7.09% <0.00%> (-0.08%)	⬇️
cmd/utils/dev.go	39.36% <0.00%> (-10.64%)	⬇️
pkg/okteto/secrets.go	0.00% <0.00%> (ø)

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[derek]

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