socks5 support for http(s)_proxy

[clement-igonet]

When installing agent on remote host, wget or curl is used to download mandatory package.

• wget is the first choice
• curl is behind

However, when the remote host rely on a socks5 proxy (defining http_proxy/https_proxy env vars):

• wget does not support socks5 protocol
• curl does

So, a fix would be to use curl:

• either curl only (no wget)
• or curl as a first choice (before wget check)

Before (KO):

    if [[ ! -z $(which wget) ]]; then
        wget --tries=3 --timeout=10 --continue --no-verbose -O vscode-server.tar.gz $SERVER_DOWNLOAD_URL
    elif [[ ! -z $(which curl) ]]; then
        curl --retry 3 --connect-timeout 10 --location --show-error --silent --output vscode-server.tar.gz $SERVER_DOWNLOAD_URL

After (OK):

    if [[ ! -z $(which curl) ]]; then
        curl --retry 3 --connect-timeout 10 --location --show-error --silent --output vscode-server.tar.gz $SERVER_DOWNLOAD_URL
    elif [[ ! -z $(which wget) ]]; then
        wget --tries=3 --timeout=10 --continue --no-verbose -O vscode-server.tar.gz $SERVER_DOWNLOAD_URL