net/url: add URL.Masked()

[nrxr]

Add method to mask the password in an URL, it's a derived method from
String() that's safe to be shown in logs.

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Message from Matt Layher:

Patch Set 1: Code-Review-1

Sorry, I don't think this is a necessary addition to the standard library. Why not add this helper where you need it?

A proposal issue is the proper place to discuss this idea, rather than submitting a change.

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Message from nrxr:

Patch Set 1:

Patch Set 1: Code-Review-1

Sorry, I don't think this is a necessary addition to the standard library. Why not add this helper where you need it?

A proposal issue is the proper place to discuss this idea, rather than submitting a change.

Hi Matt,

Indeed, I already have it as a helper for myself (see: https://github.com/nrxr/maskpass). My proposal for addition comes as I was listening today to the Go Time podcast about security (see: https://pca.st/nzc8wpta) and I saw more people could be using it as it's very common to output URLs to logs.

It was my thinking at the moment of writing the patch set that maybe having a log-friendly mode in the standard library for something as regularly used as URLs would be really helpful instead of leaving it to helpers.

I understand if it's deemed unnecessary, my intention was to propose a sensible default for something that may create security issues for a regular developer.

Let me know if the consensus is that I should be submitting this as a proposal issue instead and I'll do just that.

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