ETRecord generation fails for mv3 with cortex_m.minimum tensor constants

[psiddh]

▎ Title: Fix ETRecord serialization for cortex-m mv3 model

▎ ETRecord generation throws an exception when serializing the mv3 model exported with cortex-m55+int8 target. The root cause is the serializer
hitting an unsupported tensor constant type (cortex_m.minimum) during generate_etrecord().

▎ Currently worked around in aot_arm_compiler.py with a try/except that makes ETRecord generation non-fatal when --bundleio is the primary
intent. The .bpte/.pte are saved before ETRecord is attempted so model export is unblocked.

▎ Steps to reproduce:
▎ python -m examples.arm.aot_arm_compiler -m mv3 --target=cortex-m55+int8 --quantize --bundleio --etrecord

▎ Expected: ETRecord file generated successfully
▎ Actual: Exception during serialization (see warning log)

▎ Ref: PR #18311

Originally posted by @rascani in #18311 (comment)