Replace Fastparse by Scala Parser Combinators

[alonsodomin]

The internal parser implementation based on Fastparse has becomed obsolete since the it moved to version 2.x, and support for Scala 2.13 and/or Scala Native will not happen for the 1.x version.

After several failed attempts on upgrading the parser to FastParse 2.x, I gave up due different reasons, from the new ackward syntax to change in behaviour of the actual parsers, which means that the whole parsing process needs to be re-written from scratch.

After playing with Scala Parser Combinators, I've seen that most of the code of the parser can be left unchanged while still preserving its original behaviour. Parser combinators already supports Scala Native and Scala 2.13-M5, so with this change we are one step closer to new Scala versions and in a more stable codebase.

[codecov-io]

Codecov Report

Merging #138 into master will decrease coverage by 0.05%.
The diff coverage is 95.04%.

@@            Coverage Diff             @@
##           master     #138      +/-   ##
==========================================
- Coverage   91.54%   91.49%   -0.06%     
==========================================
  Files          67       69       +2     
  Lines        1147     1187      +40     
  Branches       40       39       -1     
==========================================
+ Hits         1050     1086      +36     
- Misses         97      101       +4

Impacted Files	Coverage Δ
...les/core/shared/src/main/scala/cron4s/errors.scala	85.71% <ø> (ø)	⬆️
.../shared/src/main/scala/cron4s/parsing/parser.scala	100% <100%> (ø)
...re/shared/src/main/scala/cron4s/parsing/base.scala	100% <100%> (ø)
...dules/core/shared/src/main/scala/cron4s/Cron.scala	100% <100%> (ø)	⬆️
...re/shared/src/main/scala/cron4s/Interpolator.scala	66.66% <66.66%> (ø)	⬆️
...e/shared/src/main/scala/cron4s/parsing/lexer.scala	89.47% <89.47%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c5cdc8a...8da20b7. Read the comment docs.