Improve drmemtrace docs: partition options list by mode and tool

[derekbruening]

Some suggested improvements to https://dynamorio.org/sec_drcachesim_ops.html and overall drmemtrace framework use:

• Partition the options list by scope (the DROPTION_SCOPE_* parameters) so it's clear what applies to tracing, what applies to post-processing for offline (may need extra info for this?), what applies to analysis tools, and what applies to the launcher.

• Rename the page so it's clear it's not just "simulator options".

• Rename the launcher from "drcachesim" or provide an alias "drmemtrace"?

[derekbruening]

Rename the launcher from "drcachesim" or provide an alias "drmemtrace"?

This is split under #6660