[Wishlist] Remove all date code

[TinCanTech]

This includes:

• Status reports.
• Option --fix-offset.

EasyRSA should not dabble in date related code.

Background information:
The reason for ALL date related code was as a prerequisite of the original version of renew. #286

This prerequisite was to arbitrate an acceptable period, within which a certificate was a viable candidate for renewal. The default chosen was 30 days before expiry. (At that time, an existing certificate had been signed for 10 years..)

This prerequisite introduced the HARD requirement for EasyRSA to calculate dates in various shells.

This arbitrary prerequisite has subsequently been discarded.

The current version of renew does not require that a certificate be within any period of expiry, before it can be renewed. A certificate can be renewed immediately, if desired.

There is no longer any reason for EasyRSA to attempt to use date.

Size-wise -- Current: 151kB, expected: 120kB (~10kB)

[TinCanTech]

First stage: Group ALL date related code together.

Translation of CA database dates for reports is still viable.

[TinCanTech]

Fixed dates can be reworked to use the same method as --passin and --passout. IE. Pass formatted dates directly to SSL -startdate and -enddate. eg: --startdate=[YY]YYMMDDHHMMSSZ

[TinCanTech]

After merging #918 there is only one reason for Easy-RSA to manipulate dates:

• To create a period, during which, easyrsa could warn about imminent expiry.
  a.k.a. EASYRSA_CERT_RENEW, default: 90 days.
  Used by show-expire (offset_days_to_cert_date()).

This can be done without the use of date but only for SSL which supports the -dateopt iso_8601 flag. (OpenSSL v3, LibreSSL untested.)

So ... this is a good time to integrate new code, without use of date, for use with OpenSSL v3. (wishlist)

[TinCanTech]

#922 final result is as follows:

• With OpenSSL v3, easyrsa only requires date to produce a timestamp +%s for status report show-expire. A residual check remains, in order to verify that easyrsa calculated "seconds since epoch" matches the value produced by date.
• With OpenSSL v1, easyrsa requires date to generate a timestamp +%s from a non-ISO-8601 date string, which is produced by OpenSSL -enddate default.

All of these changes ONLY effect status reports.

[TinCanTech]

Closed via e8ad9fb