switch editor_button to new LTI tool finder
switch editor_button to new LTI tool finder

why:
* almost every LTI placement is using all_tools_for/
Lti::ContextToolFinder to get the tools for displaying
* editor_button was one placement using a bespoke query that can be
drop-in replaced

closes INTEROP-7662
flag=none

test plan:
* specs should still pass since this is a drop-in replacement
* create a 1.1 test tool here:
https://lti-1p1-test-tool.vercel.app/?index
* include the editor_button placement and click Generate again
* install the tool in an account
* bonus: install the tool in both a CMC parent and CMC cross-shard
child account
* the tool(s) should show up in the RCE external tool list (plug
button on the toolbar)
* bonus: delete one of the tools and it doesn't show up

Change-Id: I986c7c07f2a5552fbbd36e5218b8e89070b78069
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/301766
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Paul Gray <3149ce154c2973056dc41a7285470812d38f164a@instructure.com>
Reviewed-by: Evan Battaglia <e557ffdfc4b80aab44858030b0ae5370b86cb7b1@instructure.com>
QA-Review: Paul Gray <3149ce154c2973056dc41a7285470812d38f164a@instructure.com>
Product-Review: Xander Moffatt <27f70fe194da423604e6e0a63a3de19814736fa9@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms