Fix codegen and macro edge cases

[k-bx]

Summary

• avoid generated FromQueryResult/model identifier collisions with fields named row or pre
• support active enums containing a variant named Error
• add an option to include generated columns during entity generation and omit PostgreSQL partial unique constraints from generated entity metadata

Validation

• cargo test -p sea-orm-macros --test derive_active_enum_test --test derive_entity_model_column_name_test
• cargo test --manifest-path sea-orm-cli/Cargo.toml --lib test_generate_entity_skips_postgres_partial_unique_constraints

[k-bx]

Implemented the review feedback in PR #3158. I replaced the generated signature in with (as requested). Commit: 62b5411.

[k-bx]

Implemented the review feedback in PR #3158. I replaced the generated TryFrom<&str> signature in ActiveEnum with std::result::Result<Self, sea_orm::DbErr> as requested.
Commit: 62b5411.

[Huliiiiii]

I'd like to merge the macro hygiene part first. Could you split the new CLI flag changes into a separate PR?