feat: add latency flag

[ayuhito]

Closes #8. Adds a new --latency flag to relevant commands as a method to quickly gather latency numbers.

Relevant screenshots:
Ping

DNS

HTTP

[ayuhito]

@jimaek, let me know if we should change how they look.

Regarding MTR, I was wondering whether you wanted to print out the individual stats for every hop? I'm not sure if that was your intention similar to traceroute.

[jimaek]

Regarding MTR, I was wondering whether you wanted to print out the individual stats for every hop? I'm not sure if that was your intention similar to traceroute

Every hop makes no sense I think (JSON can be used for that), just total similar to the rest

[ayuhito]

Regarding MTR, I was wondering whether you wanted to print out the individual stats for every hop? I'm not sure if that was your intention similar to traceroute

Every hop makes no sense I think (JSON can be used for that), just total similar to the rest

My point is that there is no total stat. Stats are given per hop only.

[jimaek]

Then no support for mtr then I think