Improve macOS version information in telemetry (#37185)

macOS versions are currently reported as `macOS 26.0.0`.
But this makes it impossible to differentiate amongst macOS Beta
releases which have the same version number (`X.0.0`) but are different
builds.

This PR adds build number info to `os_version` for macOS Betas and
[Rapid Security Response](https://support.apple.com/en-us/102657)
release that have identical version numbers to stable release, but have
different builds numbers. We can differentiate them because the build
numbers end with a letter.

| Version | Before | After |
| - | - | - | 
| macOS Sonoma 14.7.8 | 14.7.8 | 14.7.8 |
| macOS Sequoia 15.6.1 | 15.6.1 | 15.6.1 |
| mcOS Ventura 13.3.1 | 13.3.1 | 13.3.1 |
| macOS Ventura 13.3.1 (a) |  13.3.1 | 13.3.1 (Build 22E772610a) |
| macOS Tahoe 26.0.0 (Beta1) | 26.0.0 | 26.0.0 (Build 25A5316a) |
| macOS Tahoe 26.0.0 (Beta5) | 26.0.0 | 26.0.0 (Build 25A5349a) | 

This should cause minimal telemetry changes and only impacting a macOS
betas and a couple specific older macOS versions, but will allow
differentiation between macOS beta releases in GitHub issues.

Alternatives:
1. Leave as-is (can't differentiate between macOS beta builds)
2. Always include build number info (impacts telemetry; more consistent
going forward; differentiates non-final Release Candidates which don't
include a trailing letter)

I couldn't find a cocoa method to retrieve macOS build number, so I
switched dependencies from `cocoa` to `objc2-foundation` in the client
crate. We already depend upon this crate as a dependency of
`blade-graphics` so I matched the features of that and so workspace-hack
doesn't change.

https://github.com/zed-industries/zed/blob/1ebc69a44708f344449c0c9d47e33b414277adec/tooling/workspace-hack/Cargo.toml#L355

Release Notes:

- N/A

Cargo.lock

@@ -3070,7 +3070,6 @@ dependencies = [
  "clock",
  "cloud_api_client",
  "cloud_llm_client",
- "cocoa 0.26.0",
  "collections",
  "credentials_provider",
  "derive_more",
@@ -3083,6 +3082,7 @@ dependencies = [
  "http_client_tls",
  "httparse",
  "log",
+ "objc2-foundation",
  "parking_lot",
  "paths",
  "postage",