Introduce rc-zip-sync, rc-zip-tokio

[fasterthanlime]

This (WIP) aims to close #45.

Async Rust is a tad friendlier now, let's see how it works out this time.

(Although my ultimate goal is to tackle #44, adding back the async interface is needed to make sure the state machines are truly sans-io, and to figure out what the API should look like.)

[codecov-commenter]

Codecov Report

Attention: 485 lines in your changes are missing coverage. Please review.

Comparison is base (1016c80) 71.85% compared to head (a532d35) 74.27%.

Files	Patch %	Lines
rc-zip/src/parse/mode.rs	24.39%	93 Missing :warning:
rc-zip/src/parse/archive.rs	43.66%	40 Missing :warning:
rc-zip/src/fsm/entry/mod.rs	78.80%	39 Missing :warning:
rc-zip/src/parse/version.rs	22.00%	39 Missing :warning:
rc-zip/src/parse/extra_field.rs	75.22%	27 Missing :warning:
rc-zip/src/parse/local.rs	73.73%	26 Missing :warning:
rc-zip/src/fsm/archive.rs	76.28%	23 Missing :warning:
rc-zip/src/parse/eocd.rs	84.13%	23 Missing :warning:
rc-zip/src/fsm/entry/deflate_dec.rs	73.17%	22 Missing :warning:
rc-zip/src/fsm/entry/lzma_dec.rs	77.55%	22 Missing :warning:
... and 11 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #60 +/- ## ========================================== + Coverage 71.85% 74.27% +2.41% ========================================== Files 21 24 +3 Lines 1549 2192 +643 ========================================== + Hits 1113 1628 +515 - Misses 436 564 +128 ```

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