Add missing architectures

[egonelbre]

Currently missing:

• 386 — Support 386 #3 (v0.2.0)
• arm — Support arm (32-bit) #4 (v0.2.0)
• riscv64 — Support riscv64 #5 (v0.2.0)
• ppc64 / ppc64le — Support ppc64 / ppc64le #6 (v0.2.0)
• s390x — Support s390x #7 (v0.2.0)
• loong64 — Support loong64 #8 (v0.2.0)
• mips / mipsle / mips64 / mips64le — Support mips / mipsle / mips64 / mips64le #9 (parked: no pure-Go disassembler, see cmd/objdump: implement mips disassembler golang/go#19158)
• wasm — Support wasm #10 (v0.2.0)

[egonelbre]

All architectures except mips shipped in v0.2.0; mips stays tracked in #9 pending an upstream golang.org/x/arch decoder.