Add support for transaction source

[AbhiPrasad]

Problem Statement

As per getsentry/develop#624, we now have to start adding a source label that indicates how a transaction name was generated.

See more details here: #5342

Solution Brainstorm

• Add ability to add source to transactions feat(tracing): Add transaction source field #5367
  • transaction.setMetadata({ source: SOURCE_NAME })
  • Add tests
• Update Router integrations
  • React Router v3 ref(react): Add source to react-router-v3 #5377
  • React Router v4/v5 ref(react): Add transaction source for react router v4/v5 #5384
  • React Router v6 ref(react): Add transaction source for react router v6 #5385
  • Angular ref(angular): Add transaction source for Angular Router #5382
  • Vue feat(vue): Add transaction source to VueRouter instrumentation #5381
  • Nextjs feat(nextjs): Record transaction name source when creating transactions #5391
  • Custom instrumentation feat(tracing): Record transaction name source when name set directly #5396
  • Default instrumentation ref(tracing): Add transaction source to default router #5386
  • Serverless ref(serverless): Add transaction source #5394
  • Remix ref(remix): Add transaction source #5398
• Release Changelog: meta: 7.6.0 CHANGELOG #5397