Add Name() function to Logger struct

[rexywork]

Related to #1200

This PR add Name() function to Logger struct which will return the Logger's Name.
By default, Logger's name is empty if not set so for Unnamed Logger it will return empty string.

Please let me know which file test that I should include for testing this function and I will include the unit test.
Thank you.

[CLAassistant]

All committers have signed the CLA.

[abhinav]

LGTM.
CC @mway @prashantv @sywhang

[mway]

lgtm

[codecov]

Codecov Report

Merging #1273 (13d4936) into master (845ca51) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1273   +/-   ##
=======================================
  Coverage   98.08%   98.08%           
=======================================
  Files          50       50           
  Lines        3240     3242    +2     
=======================================
+ Hits         3178     3180    +2     
  Misses         53       53           
  Partials        9        9           

Impacted Files	Coverage Δ
logger.go	96.55% <100.00%> (+0.03%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[sywhang]

Thanks for the PR!

[rexywork]

@abhinav @sywhang @mway Seems I need to add test for the Name() function to pass the coverage.
After looking the test, I found func TestLoggerNames(t *testing.T) here: https://github.com/uber-go/zap/blob/master/logger_test.go#L319
Should we just adjust this test? For example, in here and here, we can change:
logs.AllUntimed()[0].LoggerName to log.Name() or log.base.Name() for SugaredLogger (Instead of getting the LoggerName from the Entry, we can get directly from Logger variables)
What do you think? If you agree, I can push new changes. Thank you

[mway]

Instead of replacing (because we still want to validate that entries have the correct logger name), just adding a second check against the expected logger name should be fine.

Thank you!

[rexywork]

@mway Ah I see, I will add a line check in the same test function since it kind of weird to separate as new test function.
Thank you for the quick response!

[rexywork]

@mway @abhinav @sywhang I already adjust the test and the coverage check already passed.
Please help me review and kindly help to merge if there are no additional request. Thank you

[mway]

Thanks @rexywork!