feat: Implement parsing of provider build output.

[Junkern]

What does this do / why do we need it?

Some providers use go build -o to place the final binary somewhere different than the usual $GOPATH/bin location. Until now we assumed that every provider binary is placed at the $GOPATH/bin location. This is not the case for https://github.com/russellcardullo/terraform-provider-pingdom

How this PR fixes the problem?

Parse the build output to see if there is a go build -o directive used somewhere.

Check lists

• Test passed
• Coding style (indentation, etc)

Which issue(s) does this PR fix?

fixes #81
fixes #2

[coveralls]

Pull Request Test Coverage Report for Build 2718411651

• 12 of 25 (48.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.09%) to 61.937%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/app/install.go	12	25	48.0%

Totals
Change from base Build 2711314397:	-0.09%
Covered Lines:	275
Relevant Lines:	444

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💛 - Coveralls