feat(nav): Update alerts links to /issues/alerts/

[malwilley]

Ref #84018

The new nav structure moves /alerts/ to /issues/alerts/.

To facilitate the transition, I'm adding a util makeAlertsPathname() that will check a feature flag to decide which link to generate.

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
8480	1	8479	3

View the top 1 failed test(s) by shortest run time

CreateAlertFromViewButton redirects to alert wizard with no project

Stack Traces | 0.041s run time

Error: expect(jest.fn()).toHaveBeenCalledWith(...expected)

Expected: ".../org-slug/alerts/wizard/", ObjectContaining {"params": ObjectContaining {"orgId": "org-slug"}}
Received: ".../org-slug/alerts/wizard/?", {"createHref": [Function mockConstructor], "createPath": [Function mockConstructor], "go": [Function mockConstructor], "goBack": [Function mockConstructor], "goForward": [Function mockConstructor], "isActive": [Function mockConstructor], "location": {"action": "PUSH", "hash": "", "key": "", "pathname": "/mock-pathname/", "query": {}, "search": "", "state": null}, "params": {"orgId": "org-slug", "projectId": "project-slug"}, "push": [Function mockConstructor], "replace": [Function mockConstructor], "routes": [], "setRouteLeaveHook": [Function mockConstructor]}

Number of calls: 1
    at Object.<anonymous> (.../app/components/createAlertButton.spec.tsx:203:36)

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[getsentry-bot]

PR reverted: 34bd16d

[gaprl]

Reverting as this has broken accessing uptime monitors from back-end insights: https://github.com/getsentry/sentry/pull/85005/files#diff-7edef5f8c8223b8140546bcc13f7b9184e14fe27e725d13d2aa327610b76adfaR55-R58