This PR renames `language::Buffer::new` to `language::Buffer::local` and
simplifies its interface. Instead of taking a replica id (which should
always be 0 for the local case) and a `BufferId`, which was awkward and
verbose to construct, it simply takes text and a `cx`.
It uses the `cx` to derive a `BufferId` from the `EntityId` associated
with the `cx`, which should always be positive based on the following
analysis...
We convert the entity id to a u64 using this method on `EntityId`, which
is defined by macros in the `slotmap` crate:
```rust
pub fn as_ffi(self) -> u64 {
(u64::from(self.version.get()) << 32) | u64::from(self.idx)
}
```
If you look at the type of `version` in `KeyData`, it is non-zero:
```rust
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct KeyData {
idx: u32,
version: NonZeroU32,
}
```
This commit also adds `Context::reserve_model` and
`Context::insert_model` to determine a model's entity ID before it is
created, which we need in order to assign a `BufferId` in the background
when loading a buffer asynchronously.
Release Notes:
- N/A
---------
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>