[macOS] Add Xcode 26.1 beta to macOS 15 and macOS 26 (#13085)

---------

Co-authored-by: Erik Bershel <110455084+erik-bershel@users.noreply.github.com>

Author: archita105

images/macos/toolsets/toolset-15.json

@@ -3,6 +3,14 @@
         "default": "16.4",
         "x64": {
             "versions": [
+                {
+                    "link": "26.1_beta",
+                    "filename": "26.1_beta_Universal",
+                    "version": "26.1-Beta+17B5025f",
+                    "symlinks": ["26.1"],
+                    "sha256": "432f6cb936ec9547e1075e5a969309e6e0497199810bcb79e10423fa5408891c",
+                    "install_runtimes": "none"
+                },
                 {
                     "link": "26.0.1",
                     "filename": "26.0.1_Universal",
@@ -55,6 +63,14 @@
         },
         "arm64":{
             "versions": [
+                {
+                    "link": "26.1_beta",
+                    "filename": "26.1_beta_Universal",
+                    "version": "26.1-Beta+17B5025f",
+                    "symlinks": ["26.1"],
+                    "sha256": "432f6cb936ec9547e1075e5a969309e6e0497199810bcb79e10423fa5408891c",
+                    "install_runtimes": "none"
+                },
                 {
                     "link": "26.0.1",
                     "filename": "26.0.1_Universal",

images/macos/toolsets/toolset-26.json

@@ -3,6 +3,14 @@
         "default": "26.0.1",
         "arm64":{
             "versions": [
+                {
+                    "link": "26.1_beta",
+                    "filename": "26.1_beta_Universal",
+                    "version": "26.1-Beta+17B5025f",
+                    "symlinks": ["26.1"],
+                    "sha256": "432f6cb936ec9547e1075e5a969309e6e0497199810bcb79e10423fa5408891c",
+                    "install_runtimes": "default"
+                },
                 {
                     "link": "26.0.1",
                     "filename": "26.0.1_Universal",