[cr132] //chrome/browser/ui/javascript_dialogs modularised

This makes it necessary to declare this target as a dep of
`//brave/browser/ui`.

Chromium change:
https://chromium.googlesource.com/chromium/src/+/b2877940e18b82a911ba18dfca2ea00988f944b6

commit b2877940e18b82a911ba18dfca2ea00988f944b6
Author: Antonio Gomes <[email protected]>
Date:   Tue Oct 15 10:37:05 2024 +0000

    Modularize chrome/browser/ui/javascript_dialogs

    This CL adds to chrome/browser/ui/javascript_dialogs its own BUILD.gn file.
    Given that there is a circular dependency against both //c/b/:b and
    //c/b/ui:ui, an "impl" GN target was added in order to confine the
    circular dependencies. Once the modularization advances, both
    :javascript_dialogs and :impl GN targets should be unified.

    No behavior change expected.

    [email protected]

    Bug: 372506006

browser/ui/BUILD.gn

@@ -620,6 +620,7 @@ source_set("ui") {
       "//chrome/browser/devtools",
       "//chrome/browser/ui/download",
       "//chrome/browser/ui/exclusive_access",
+      "//chrome/browser/ui/javascript_dialogs",
       "//chrome/browser/ui/views/bubble",
       "//chrome/browser/ui/views/toolbar",
       "//components/bookmarks/browser",