Assign custom certificates to multiple proxy hosts at the same time

[vlakius]

Is your feature request related to a problem? Please describe.
First of all, thank you for your hard work. I love the project and use it everywhere.

I have several instances of NPM with more than 50 proxy hosts with custom SSL wildcard certificates. The problem is that when they expire, I have to change the certificates one by one on all the proxy hosts, with the consequent risk of forgetting some of them, as well as it being a repetitive and tedious task.

Describe the solution you'd like
The ideal solution would be to be able to replace the custom certificate so that you don't have to reassign the certificate on all proxy hosts.
Alternatively, it would be nice to be able to assign the certificate en masse to all desired proxy hosts (I'm thinking of a table with selectable checkboxes and an “Assign certificate” button).

Describe alternatives you've considered
I considered creating a custom script that uses APIs to perform operations on a large scale, or overwriting the certificate file and restarting NPM, but I haven't tested whether this works yet. If anyone has already found a workaround, please write it below.

EDIT
Related #4769

and this PR #4425

Sorry, I didn't see that.