Enable synonym mapping without "gprofiler"

[bschilder]

Functions like map_genes and aggregate_genes rely on "gprofiler" as the only method that can do gene synonym matching.

However, this requires internet access and the gprofiler databases sometime breaks down randomly.
For example, today during checks:

── Error (test-run_benchmark.R:3:5): run_benchmark works ───────────────────────
Error in `gprofiler2::gconvert(query = ranges, organism = species, ...)`: Bad request, response code 400
Backtrace:

Would be good to have non-gprofiler alternatives for all functions, including these.