Use libwebrtc's DesktopCapturer for screen capture

This adds support for screen sharing on Wayland (fixes #28754).

libwebrtc replaces scap, which aims to be cross platform but was only
used on Windows and X11. The X11 support relied on an out-of-tree branch
on which the original author closed their own pull request
(CapSoftware/scap#124). This also replaces Zed's
platform-specific code on macOS. Switching to a single cross platform
library simplifies the code by removing the need for Zed to have its own
traits for cross platform abstraction.

Author: Be-ing

.github/workflows/release.yml

@@ -44,6 +44,9 @@ jobs:
   run_tests_linux:
     if: (github.repository_owner == 'zed-industries' || github.repository_owner == 'zed-extensions')
     runs-on: namespace-profile-16x32-ubuntu-2204
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -123,6 +126,9 @@ jobs:
   check_scripts:
     if: (github.repository_owner == 'zed-industries' || github.repository_owner == 'zed-extensions')
     runs-on: namespace-profile-2x4-ubuntu-2404
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683

.github/workflows/run_tests.yml

@@ -61,6 +61,9 @@ jobs:
   check_style:
     if: (github.repository_owner == 'zed-industries' || github.repository_owner == 'zed-extensions')
     runs-on: namespace-profile-4x8-ubuntu-2204
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -130,6 +133,9 @@ jobs:
     - orchestrate
     if: needs.orchestrate.outputs.run_tests == 'true'
     runs-on: namespace-profile-16x32-ubuntu-2204
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -213,6 +219,9 @@ jobs:
     - orchestrate
     if: needs.orchestrate.outputs.run_tests == 'true'
     runs-on: namespace-profile-16x32-ubuntu-2204
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -252,6 +261,9 @@ jobs:
     - orchestrate
     if: needs.orchestrate.outputs.run_tests == 'true'
     runs-on: namespace-profile-8x16-ubuntu-2204
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -292,6 +304,9 @@ jobs:
     - orchestrate
     if: needs.orchestrate.outputs.run_tests == 'true'
     runs-on: namespace-profile-2x4-ubuntu-2404
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -324,6 +339,9 @@ jobs:
     - orchestrate
     if: needs.orchestrate.outputs.run_docs == 'true'
     runs-on: namespace-profile-8x16-ubuntu-2204
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
@@ -394,6 +412,9 @@ jobs:
     - orchestrate
     if: needs.orchestrate.outputs.run_action_checks == 'true'
     runs-on: namespace-profile-2x4-ubuntu-2404
+    env:
+      CC: clang
+      CXX: clang++
     steps:
     - name: steps::checkout_repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683