Move the custom request handler call after the main ACL check

[sergeyrud-stripe]

Running a custom request handler after a successful ACL check is more useful for certain use cases. I.e. if a request is denied by checkIfRequestShouldBeProxied, this request might be irrelevant for CustomRequestHandler.

[github-actions]

Pull Request Test Coverage Report for Build 5068985840

• 13 of 13 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.04%) to 62.476%

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Totals
Change from base Build 5024495973:	-0.04%
Covered Lines:	1292
Relevant Lines:	2068

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 5068985840

Warning: This coverage report may be inaccurate.

We've detected an issue with your CI configuration that might affect the accuracy of this pull request's coverage report.
To ensure accuracy in future PRs, please see these guidelines.
A quick fix for this PR: rebase it; your next report should be accurate.

• 12 of 12 (100.0%) changed or added relevant lines in 1 file are covered.
• 40 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 62.476%

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Files with Coverage Reduction	New Missed Lines	%
pkg/smokescreen/config.go	40	34.26%

Totals
Change from base Build 5024495973:	-0.04%
Covered Lines:	1292
Relevant Lines:	2068

---

💛 - Coveralls

[kevinv-stripe]

LGTM. Thanks for the PR!

For other smokescreen users: if this change breaks your implementation please file an issue and we'll address it ASAP.