Actions:
1. Remove unused functions from misc_os_dependent.h
2. Move three remaining functions, get_gmt_time, get_ns_count, and get_tick_count into time_helper.h
3. Remove unused functions from time_helper.h
4. Refactor get_ns_count and get_internet_time_str and get_time_interval_string
5. Remove/add includes as needed
Relevant commits on the old PR:
a9fbe52b02ffab451e90c977459fea4642731cd1
9a59b131c4ed1be8afe238fff3780fe203c65a46
7fa9e2817df9b9ef3f0290f7f86357939829e588