Added `insert()`, `erase()`, and `reserve()`/`resize()` support to vector.

[adamshapiro0]

Note: This is currently based on top of https://github.com/serge-sans-paille/frozen/pull/123, which has yet to be merged, and as a result includes all of the commits from that PR. Only the last 3 commits in this PR are relevant here. Once https://github.com/serge-sans-paille/frozen/pull/123 is merged, I will update this PR accordingly.