Fix ACAS use case in ACETONE-based exporter

Context

Following a series of changes to support more flexible templates, the ACAS use case was no longer supported. This MR introduces a number of fixes and changes to get the ACAS running again (and support a wider range of constraints on supported operators). The MR also introduces support for the benchmarking API introduced in Aidge 0.6.

Modified files

• templates/*: support for more flexible dimensions; reduce the overheads on dimension broadcasting; match tensor names with SONNX specification.
• tests/*: simplify test harnesses using the v0.6 benchmarking API; standardise parameter generation to better fit with hypothesis testing.