Implement human-readable durations in the config

[0x009922]

Description

Enhance HumanDuration type to actually parse a human-readable string:

https://github.com/hyperledger/iroha/blob/964476722e2a219becaacdb3676ca058ec5748cd/config/base/src/lib.rs#L23-L27

Specification

Here is an excerpt from the configuration reference draft:

Duration is specified as a human-readable string:

value1 = "1sec"
value2 = "1hour 12min 5s"
value3 = "2years 2min 12us"
value4 = "550ms"

The duration string is a concatenation of time spans. Each time span is an
integer number and a suffix. Supported suffixes:

• nsec, ns — nanoseconds
• usec, us — microseconds
• msec, ms — milliseconds
• seconds, second, sec, s
• minutes, minute, min, m
• hours, hour, hr, h
• days, day, d
• weeks, week, w
• months, month, M — defined as $30.44$ days
• years, year, y — defined as $365.25$ days

I used humantime crate for reference. Maybe it can be used as is. Otherwise, it is straighforward (and quite interesting!) to write our own parser with something like winnow.

[mversic]

as discussed here I'm not sure we want to complicate config files. Simple fixed suffix on the field name should suffice IMO. We need to discuss this before proceeding

[0x009922]

There was a discussion in favor of human-readable strings here:

• Tracking Issue for Configuration Reference as per RFC iroha-2-docs#392