[Bench] Separate group for native SubmitGraph cases and adjust naming

[mmichel11]

Fixes the SubmitGraph display issues in the benchmark dashboard with the following adjustments:

• The "graph emulation" naming has been switched, and L0 / UR graph benchmarks are referred to as "native" to align with what we plan to call this feature in SYCL.
• Due to technical differences in the underlying APIs, native graph APIs are assigned their own grouping as cross-comparing may lead to false performance conclusions.