Allow hiding C++ template parameters (and other similar things) in tree explorer

C++ templates can get super long and are painful to look at in most cases. We should ideally add support to disable template visualization in the flamegraph.

Note that this should be done at the data level *not* the viz level so we get automatic merging across different sample types.

Start by locating the tree explorer/flamegraph data pipeline and the C++ symbol or name normalization path. Determine where template parameters can be hidden before aggregation rather than only in visualization; done means the option works for flamegraphs and automatically merges samples that differ only in those parameters.

Written by the indexing model from the issue text.