Enable the RpcClient to send requests to Bitcoin Core over a Unix socket.

[robertmin1]

Enable the RpcClient to send requests to Bitcoin Core over a Unix socket.
Issue #2149

[SulaimanAminuBarkindo]

Thanks for this pull request!
Overall, this pull request looks good and seems like a valuable addition to btcd. To further improve its usability and clarity, I have a couple of suggestions:

Example Usage: It would be helpful to add some example usage demonstrations in the examples folder for the rpcclient with this new functionality. This would make it easier for users to understand how to use the new feature in practice.

Testing: To further improve the clarity of the pull request, consider adding some steps to the PR description outlining how to test the newly implemented functionality with Unix sockets. This would be beneficial for both reviewers and future users.

[robertmin1]

Great! I've included an example that should clarify how to test it further. The only tricky part is that a host needs to be passed to avoid raising errors. The value doesn't matter as long as it's valid. If the client has a default value, this shouldn't be a problem. Perhaps when setting the DialContext, we can hard code a value like localhostunix.

[SulaimanAminuBarkindo]

Thank you for providing the example files.

LGTM

[robertmin1]

Updated the code. I didn't set a default port when calling ParseAddressString since the host doesn't seem to have one.
Additionally, I used ParseAddressString to set a placeholder for Unix sockets in handleSendPostMessage in a cleaner way

[coveralls]

Pull Request Test Coverage Report for Build 8772206116

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 3 of 19 (15.79%) changed or added relevant lines in 1 file are covered.
• 243 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.01%) to 56.873%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rpcclient/infrastructure.go	3	19	15.79%

Files with Coverage Reduction	New Missed Lines	%
chaincfg/params.go	4	97.35%
peer/peer.go	6	74.16%
rpcclient/infrastructure.go	233	39.21%

Totals
Change from base Build 8802845904:	-0.01%
Covered Lines:	29452
Relevant Lines:	51786

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💛 - Coveralls