Firstly, this commit requires that all types are signless in the strict
mode of the validation pass. This is because signless types on
operations are required by the TOSA specification. The "strict" mode in
the validation pass is the final check for TOSA conformance to the
specification, which can often be used for conversion to other formats.
In addition, a conversion pass `--tosa-convert-integer-type-to-signless`
is provided to allow a user to convert all integer types to signless.
The intention is that this pass can be run before the validation pass.
Following use of this pass, input/output information should be carried
independently by the user.
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