feat: implement `dex` module

[delvinru]

Hi, I have implemented the dex module.

The current version is incompatible with the old version, because in that implementation there were not very convenient methods and names of exported variables.

What has been changed:

• Added new method checksum for computing adler-32 checksum;
• Added new method signature for computing sha-1 signature;
• Added new methods: contains_strings, contains_methods, contains_classes - honestly, I doubt their usefulness, but I decided to leave them, because binary search is used under the hood, since the strings are guaranteed to be sorted by the format itself;
• Methods removed: has_method_string, has_method_and_class_string, has_method_regexp, has_method_and_class_regexp, has_class_string, has_class_regexp (as far as I can see on github, no one used them anyway); And in practice, quite useless calls;
• Changed access to strings, methods, types, protos and classes. I've made them more informative and user-friendly, unlike the previous implementation;
• Added documentation, because on https://yara.readthedocs.io / there is no information about dex module;

Fuzzing testing was started locally, all errors were fixed, but I do not exclude that something else will be revealed during a long run.

Since the most difficult thing in programming is to come up with a name for variables, if there are suggestions about names in proto, then I'm ready for discussion.

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[delvinru]

@plusvic Hi, there are a lot of clippy errors in the pipeline that are not related to my code (or any my changes)

It's better to fix them in the master, and then merge them into this branch, rather than the other way around.

[delvinru]

@plusvic Hi, does this MR look okay, or do I need to add something else to merge it?

[plusvic]

@plusvic Hi, does this MR look okay, or do I need to add something else to merge it?

I'm running the fuzzer a little bit before merging it.

[delvinru]

@plusvic hi, any updates?