chore(typing): Remove sentry.search.events.datasets.filter_aliases from mypy ignore list

[shashjar]

Resolves ENG-6454.

Fixes typing in sentry.search.events.datasets.filter_aliases and removes it from the mypy ignore list.

Most errors stem from SearchValue.raw_value having a broad union type (str | float | datetime | Sequence[float] | Sequence[str]) while these filter functions always receive strings. Narrowed the types with validation at each point of use.

Changes:

• Narrow raw_value to str via isinstance in span_is_segment_converter, semver_filter_converter, semver_package_filter_converter, semver_build_filter_converter, and span_module_filter_converter
• Narrow raw_value to str | list in lowercase_search and span_status_filter_converter to handle each raw_value shape
• Filter None from builder.params.environments before passing to parse_release
• Pass environment names (list[str]) to filter_by_stage instead of Environment objects, matching its Sequence[str | int] | None signature

[linear-code]

ENG-6454

[cursor]

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