fix: sorting function for date fields

[hui00]

This Pull Request introduces sorting with HTML data-sort (timestamp-integers) and remove moment.js

1. add sort for created_at and updated_at columns
2. add sort for date_start, date_end, and to_end columns
3. remove moment-related code and dependencies

SVA-1122

[donni106]

You forgot POIs:

<td><%= toLocalDateTime(poi.updated_at) %></td>
<td><%= toLocalDateTime(poi.created_at) %></td>

I will adjust that.

[donni106]

And Tours:

<td><%= toLocalDateTime(tour.updated_at) %></td>
<td><%= toLocalDateTime(tour.created_at) %></td>

I will adjust as well.