CHIA-4241: Remove _write, since it isn't used anymore

[prozacchiwawa]

Note

Low Risk
Dead-code removal with no remaining _write references; compile-time _read and other operators are unchanged.

Overview
Removes the compiler dialect’s _write operator and all code that only supported it.

The deleted write path disassembled CLVM to IR and wrote source to disk via fs::write. The Dialect::op dispatch no longer handles _write, and get_disassembly_ver (used only for that path) is removed. Unused imports (Stream, keyword_from_atom, disassemble_to_ir_with_kw, write_ir_to_stream) are dropped.

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