Allow `router.push()` to pass `state`

[posva]

Summary

• Allow the user to pass a state property alongside path, query, and other properties to persist to history.state.
• Allow the user to read the history.state directly at this.$route.state.

Programmatic navigation:

router.push({ name: 'Details', state: { showModal: true } })
router.replace({ state: { showModal: true } })

Links

• Full Rendered Proposal

• Discussion Thread

---

Important: Do NOT comment on this PR. Please use the discussion thread linked above to provide feedback, as it provides branched discussions that are easier to follow. This also makes the edit history of the PR clearer.