Basic implementation of discoverage ttag functions from require

[AlexMost]

Original issue is here - ttag-org/ttag#44.
This PR makes it possible to discover ttag functions from require function calls

Example:

const { t } = require('ttag');

t`test`

will be extracted to

msgid "test"
msgstr ""

@Alxpy @vharitonsky @MrOrz @snowwm

[codecov]

Codecov Report

Merging #104 into master will decrease coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #104      +/-   ##
==========================================
- Coverage   96.45%   96.41%   -0.04%     
==========================================
  Files          14       14              
  Lines        1185     1200      +15     
  Branches      176      178       +2     
==========================================
+ Hits         1143     1157      +14     
- Misses         42       43       +1

Impacted Files	Coverage Δ
src/plugin.js	96.46% <100%> (+0.18%)	⬆️
src/defaults.js	100% <100%> (ø)	⬆️
src/utils.js	94.94% <100%> (-0.39%)	⬇️

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