Add support for "ethers.js" target

[Destiner]

Fixes #94.

[coveralls]

Pull Request Test Coverage Report for Build 149

• 61 of 65 (93.85%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 88.694%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/targets/ethers/generation.ts	41	45	91.11%

Totals
Change from base Build 147:	0.5%
Covered Lines:	388
Relevant Lines:	422

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💛 - Coveralls