ref(grouping): Add split enhancements to enhancement bases

[lobsterkatie]

Note: This is currently blocked by getsentry/ophio#73, which in turn is blocked by getsentry/ophio#72. Once those are merged, it will fix the failing test.

---

This is a follow-up to #90505, which enabled enhancements (stacktrace rules) to be split up into classifier and contribtues types. In this PR, such split enhancements are added the default enhancements objects (the "bases," the ones representing the rules from each grouping config), to live alongside the regular enhancements, by forcing them to be created using version 3, rather than version 2.

This means that now if non-default enhancements were to be instantiated with version 3, their split rust enhancements would actually pull in the real default rules, rather than the empty rules provided by the classifier_rust_enhancements and contributes_rust_enhancements class variables. Nothing is actually doing that right now, but this means that once we turn it on, it'll have the right data.

This PR also adds some magic methods to the EnhancementRule class, to make testing easier.

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
25299	1	25298	307

View the top 1 failed test(s) by shortest run time

tests.sentry.grouping.test_enhancer::test_basic_parsing[3]

Stack Traces | 0.103s run time

#x1B[1m#x1B[.../grouping/enhancer/__init__.py#x1B[0m:92: in get_rust_enhancements
    return RustEnhancements.from_config_structure(input, RUST_CACHE)
#x1B[1m#x1B[31mE   RuntimeError: Invalid syntax Rust Enhancements only supports config_structure version `2`#x1B[0m

#x1B[33mDuring handling of the above exception, another exception occurred:#x1B[0m
#x1B[1m#x1B[.../sentry/grouping/test_enhancer.py#x1B[0m:126: in test_basic_parsing
    assert Enhancements.from_base64_string(enhancements_str).base64_string == enhancements_str
#x1B[1m#x1B[.../grouping/enhancer/__init__.py#x1B[0m:457: in from_base64_string
    rust_enhancements = get_rust_enhancements("config_structure", pickled)
#x1B[1m#x1B[.../grouping/enhancer/__init__.py#x1B[0m:97: in get_rust_enhancements
    raise InvalidEnhancerConfig(str(e))
#x1B[1m#x1B[31mE   sentry.grouping.enhancer.exceptions.InvalidEnhancerConfig: Invalid syntax Rust Enhancements only supports config_structure version `2`#x1B[0m

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