This adds various Vec methods. Some of them are needed by Rust Binder,
and others are needed in other places. Each commit explains where it is
needed.

This series is based on top of alloc-next and rust: alloc: split
`Vec::set_len` into `Vec::{inc,dec}_len`
https://lore.kernel.org/rust-for-linux/20250416-vec-set-len-v4-0-112b222604cd@gmail.com/

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Changes in v3:
- Rebase on split `Vec::set_len` into `Vec::{inc,dec}_len`.
- Various modifications to work with inc/dec_len instead of set_len,
  with some Reviewed-by's dropped due to this.
- Move push_within_capacity impl into an unchecked variant.
- Link to v2: https://lore.kernel.org/r/20250321-vec-methods-v2-0-6d9c8a4634cb@google.com

Changes in v2:
- Add two more methods that I needed.
- Introduce some uses of set_len.
- Add example to retain.
- Simplify pop.
- Adjust 11 to 10 in push_within_capacity example.
- Link to v1: https://lore.kernel.org/r/20250320-vec-methods-v1-0-7dff5cf25fe8@google.com

---
Alice Ryhl (7):
      rust: alloc: add Vec::clear
      rust: alloc: add Vec::pop
      rust: alloc: add Vec::push_within_capacity
      rust: alloc: add Vec::drain_all
      rust: alloc: add Vec::retain
      rust: alloc: add Vec::remove
      rust: alloc: add Vec::insert_within_capacity

 rust/kernel/alloc/kvec.rs | 241 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 239 insertions(+), 2 deletions(-)
---
base-commit: 1569d07593b986b690eec0bd85a632b6712f4c2e
change-id: 20250320-vec-methods-adfa41e55311

Best regards,
-- 
Alice Ryhl <aliceryhl@google.com>