Enhanced network detection in installer

[bellegarde-c]

Many enterprise networks disallow ping and direct HTTP(s) connections.
Rework checkInternetConnection() to check DNS issues and then HTTP issues.

[mastacontrola]

Hello @bellegarde-c

I hope you're doing well, and sorry I haven't gotten back sooner.

There's a few things about this change that I'm a little confused about.

1. The $dns_command is configured but then never used.
2. I tried a site I knew didn't exist and it showed host and nslookup with a non-zero return. Maybe it existed at one point and no longer does? I, for now, have just used getent as I believe this is more versatile.

I also changed the output so the testing can be more verbose.

I added the changes into the working-1.6 branch.
I would ask you to review and make changes accordingly and instead of sending to the master please place the changes into dev-branch (Master is our release branch so we don't touch this branch until release is ready to go live)

Thank you,

[bellegarde-c]

Yes, I saw you already changed the code in dev branch just after sending this. Will report any issue and send you merge request next time I update.

regards,

[Sebastian-Roth]

@bellegarde-c @mastacontrola The changes were added to the working-1.6 branch so far but not to dev-branch yet. Would be great to get this into dev-branch as well and even better when using the exact same code changes so merging the branches later on will be easier.

[Sebastian-Roth]

Finally pushed commits to both working-1.6 (df23d1c) and dev-branch (5a3e075) to have them both use the same code. Also adjusted things a bit again.