fix: export KoaLayerType enum correctly

[cincauhangus]

Short description of the changes

KoaLayerType is an enum. It was erroneously exported as a type causing errors on in Koa setups. This breaks the configuration setup for ignoring certain Koa Layers when publishing spans.

This was working in @opentelemetry/instrumentation-koa v0.46.0, now broken in v0.50.0.

Typescript linter error:

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: cincauhangus / name: Aaron Ho (6551696, de50920)
• ✅ login: david-luna / name: David Luna (321243a)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.73%. Comparing base (a81ef5f) to head (321243a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2873   +/-   ##
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  Coverage   89.73%   89.73%           
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  Files         187      187           
  Lines        9059     9059           
  Branches     1858     1858           
=======================================
  Hits         8129     8129           
  Misses        930      930           

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[github-actions]

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[cincauhangus]

Hi @david-luna, need some assistance to get this PR approved/merged as breaks functionality from your recent commit 60612f2 (#2839)

[david-luna]

@cincauhangus thanks for the fix. Please run npm run lint:fix in the koa instrumentation folder and push the changes. Then I'll be able to approve and merge :)

[cincauhangus]

@david-luna done and ready for review/merge