Mark user owned probes in API responses

[jimaek]

If the user is authenticated when making a new measurement we should clearly mark the probes he owns in the response.
Probably a system tag? This way the user could query his own probes directly as well.

Once the API supports it we can add markers to all of our tools.

Context jsdelivr/globalping-cli#128

[MartinKolarik]

In the dashboard, add a new section "Privacy" below "Account details" with a single on/off setting "Make my probes public" and description "If enabled, your probes will be automatically tagged by u-${username} (show the personalized value here, not the template), allowing you to select them in measurements. A list of your active probes will also be available at https://globalping.io/users/${username}"

On the API, add the tag to all user's probes if the user has the setting enabled.