refactor: parsing of constraints

[baszalmstra]

Refactors the parsing of constraints (e.g. >3.1, 2.*). I also had to refactor the version parser a little bit to ensure it properly handles a version followed by .* or *. The goal of these refactors is to improve performance, provide better error messages and create a unified parser for all data types instead of partly regex, nom, and string matching.

[wolfv]

Here are my numbers (although I have no reference, so idk if things are faster or slower :)

     Running benches/parse.rs (target/release/deps/parse-eb7c46bccb24a24c)
Gnuplot not found, using plotters backend
parse simple version    time:   [107.97 ns 108.18 ns 108.41 ns]
Found 5 outliers among 100 measurements (5.00%)
  4 (4.00%) high mild
  1 (1.00%) high severe

parse complex version   time:   [658.11 ns 659.37 ns 660.74 ns]
Found 3 outliers among 100 measurements (3.00%)
  2 (2.00%) high mild
  1 (1.00%) high severe

parse logical constraint
                        time:   [44.256 ns 44.350 ns 44.462 ns]
Found 1 outliers among 100 measurements (1.00%)
  1 (1.00%) high mild

parse wildcard constraint
                        time:   [122.10 ns 122.78 ns 123.73 ns]
Found 3 outliers among 100 measurements (3.00%)
  1 (1.00%) high mild
  2 (2.00%) high severe

parse simple version spec
                        time:   [44.384 ns 44.486 ns 44.591 ns]
Found 2 outliers among 100 measurements (2.00%)
  2 (2.00%) high mild

parse complex version spec
                        time:   [50.782 ns 51.106 ns 51.408 ns]
Found 2 outliers among 100 measurements (2.00%)
  2 (2.00%) low mild

     Running unittests src/lib.rs (target/release/deps/rattler_digest-ff3bfc03e5590ce1)

running 5 tests