Call Hierarchy view should show both incoming & outgoing at the same time

[eamodio]

Issue Type: Bug

I found it confusing that the peek and view remember the direction. While there is an aspect to that which is nice (and probably desirable). It felt strange to me, that when I opened the peek it had defaulted to Calls from, but on the same keyword using show it has defaulted to Callers of and I was confused for a minute about why I was seeing different data.

IMO, I think it would be nicer if the view instead of being a toggle, it just had 2 root nodes -- one for Calls from 'foo' and Callers of 'foo'. That way there would be no disconnect from the peek to the view and the view would be showing even more information at the same time.

Refs: #85924

VS Code version: Code - Insiders 1.41.0-insider (7f1975a, 2019-12-04T10:20:42.228Z)
OS version: Windows_NT x64 10.0.19033

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz (8 x 4008)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off surface_control: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	31.93GB (17.91GB free)
Process Argv
Screen Reader	no
VM	0%

[vscodebot]

The described behavior is how it is expected to work. If you disagree, please explain what is expected and what is not in more detail. See also our issue reporting guidelines.

Happy Coding!

[jrieken]

See #16110 (comment) more background on this. We have explored the double-direction approach in March but didn't continue on it because we figured it makes things complex without adding value. Actually, VS did the same and they simplified their call hierarchy UX a few year back which influenced this but it also felt bad because each node get more children