Update module event handler scope

[iramiller]

Description

Updates each modules handler to setup a new event manager scope within the handler function that processes msgs. Modifies unit tests to assert on the response from the handler to check for events.

closes: #288

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #289 (0297f14) into main (0141016) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #289      +/-   ##
==========================================
+ Coverage   50.12%   50.13%   +0.01%     
==========================================
  Files         122      122              
  Lines       11115    11119       +4     
==========================================
+ Hits         5571     5575       +4     
  Misses       4995     4995              
  Partials      549      549              

Impacted Files	Coverage Δ
x/attribute/handler.go	83.33% <100.00%> (+1.51%)	⬆️
x/marker/handler.go	76.66% <100.00%> (+0.39%)	⬆️
x/metadata/handler.go	31.66% <100.00%> (+1.15%)	⬆️
x/name/handler.go	66.66% <100.00%> (+1.96%)	⬆️

[channa-figure]

LGTM

[piercetrey-figure]

Just pulled this down and it fixes the issue I was seeing, thanks!

[dwedul-figure]

LGTM