Revise using of rejectUnauthorized

[mmorhun]

Is your task related to a problem? Please describe.

At the moment in chectl we use rejectUnauthorized: false option when AxiosInstance makes requests to Che API.

Describe the solution you'd like

Current approach works fine, but the right way is to use specific CA certificate for such requests.
We've implemented retrieving of Che self-signed CA certificate which can be used to get the cert and pass to Axis to be able to connect to Che API without rejectUnauthorized: fasle option.
However, retrieving the cert each time chectl is run will add a few seconds to command execution time (at this point we need to make sure, that self-signed certificate is using, which could be done by checking for self-signed-certificate secret in Che's namespace). To reduce this time we may try to cache the cert in tmp directory (it will not bring a security risk as we export only public part of Che root CA certificate).

[tolusha]

Add some preflight chekcs, if cert is not valid, ask user to trust the server.

[tolusha]

Having [1] and [2] the necessity of this issue is quite low.
So I've decided not to spend time on this.

[1] #20010
[2] #19182