[WIP] refactor: timestamps

[sleepdefic1t]

Proposed changes

Current Slots implementation sometimes overflows numeric timestamps on IoT.
Official Timestamps now also use milliseconds.

This PR does the following:

• refactors and simplifies Slots.
• remedies overflow/loss of precision of numeric timestamps.
• fixes parsing of ISO8601 'Readable' Timestamps containing milliseconds.
• updates the preset Ark Networks Timestamps to correctly use milliseconds.
• sets a "dummy time" for PIO testing of IoT without a network connection.
• updates Slots tests to reflect changes.
• adds custom Slots::now() under USE_IOT flag.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (improve a current implementation without adding a new feature or fixing a bug)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Build (changes that affect the build system)
• Docs (documentation only changes)
• Test (adding missing tests or fixing existing tests)
• Other... Please describe:

Checklist

• I have read the CONTRIBUTING documentation
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[ciband]

The original slots structure and unit tests were designed to match core. I would vote to keep the interface as close to core as possible. What do the other APIs do?

[codecov-io]

Codecov Report

Merging #53 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #53      +/-   ##
==========================================
+ Coverage   61.62%   61.71%   +0.08%     
==========================================
  Files          41       40       -1     
  Lines        2567     2565       -2     
==========================================
+ Hits         1582     1583       +1     
+ Misses        985      982       -3

Impacted Files	Coverage Δ
src/include/cpp-crypto/networks/mainnet.h	100% <ø> (ø)	⬆️
src/include/cpp-crypto/networks/devnet.h	100% <ø> (ø)	⬆️
src/include/cpp-crypto/networks/testnet.h	100% <ø> (ø)	⬆️
src/utils/slot.cpp	91.66% <100%> (+7.05%)	⬆️
src/date/date.h	30.76% <0%> (+0.23%)	⬆️

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[sleepdefic1t]

@ciband

I saw they were going after matching Core.

Whatever was going on, it was overflowing timestamps on <=ESP32.
I was also unable to send transactions from the ESP32 using both Client & Crypto.

Timestamps also use milliseconds now https://explorer.ark.io:8443/api/v2/node/configuration.

After these most recent updates, I'm able to create and sign a transactions to be broadcasted via Cpp-Client:

https://dexplorer.ark.io/transaction/7745ade9c676fe7ebf9e114c61ff9065808413428f6f265da424eede55cb69de

Looks like PIO is having a fit about localTime on Linux PIO builds though.
On the fix for that.

[sleepdefic1t]

I could work on using the naming in Core though.

It just needed a good housekeeping and was holding me back on IoT.

Was able to send another one after the last build.
https://dexplorer.ark.io/transaction/112cc3f11e5a318e3898075b9984a1398ae7e695811a31ec8d22069861e6bd36

And now there's a macOS build error 😭

[sleepdefic1t]

@ciband
Correction, I don't think we're supposed to mimic Core's methods

SDK docs call for the following:

Slot

• time Get the time elapsed since network start.
• epoch Get the timestamp of the network start.

src: https://docs.ark.io/sdk/cryptography/guidelines.html#slot

[sleepdefic1t]

@faustbrian Do you have a way to retrigger the workflow for this failing test?

I suspect it’s just a random CI error.
Slots do indirectly touch the tx.builder,
but that shouldn’t cause DER encoding to throw an assertion error.

I’d feel better seeing all tests pass, and this PR is otherwise complete.

Please and thank you.