fix: wide string concatenation

[trop]

Backport of #40892

See that PR for details.

Notes: Fixed default protocol handler behavior on Windows.

[codebytere]

FTBTS:

../../electron/shell/browser/browser_win.cc(145,44): error: no member named 'AsWStringView' in namespace 'base'; did you mean 'AsWStringPiece'?
  145 |     *exe = base::StrCat({*exe, L" ", base::AsWStringView(joined_launch_args)});
      |                                      ~~~~~~^~~~~~~~~~~~~
      |                                            AsWStringPiece
../..\base/strings/string_util_win.h(94,21): note: 'AsWStringPiece' declared here
   94 | inline WStringPiece AsWStringPiece(StringPiece16 str) {
      |                     ^
1 error generated.
ninja: build stopped: subcommand failed.
gn desc out/Default v8:run_mksnapshot_default args > out/Default/default_mksnapshot_args

[ckerr]

FTBTS:

Probably needs to be base::AsWStringPiece in the older branches due to https://chromium-review.googlesource.com/c/chromium/src/+/5010979

[clavin]

2 test failures on the WoA build:

not ok 651 contentTracing stopRecording does not crash on empty string
  Timeout of 5000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (C:\projects\src\electron\spec\api-content-tracing-spec.ts)
  Error: Timeout of 5000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (C:\projects\src\electron\spec\api-content-tracing-spec.ts)
      at listOnTimeout (node:internal/timers:569:17)
      at processTimers (node:internal/timers:512:7)
not ok 652 contentTracing stopRecording calls its callback with a result file path
  Timeout of 5000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (C:\projects\src\electron\spec\api-content-tracing-spec.ts)
  Error: Timeout of 5000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (C:\projects\src\electron\spec\api-content-tracing-spec.ts)
      at listOnTimeout (node:internal/timers:569:17)
      at processTimers (node:internal/timers:512:7)

These seem unrelated and likely flakes. Happy to rerun, but the important tests for this change did pass so I'm leaning towards dismissing the two failures as flakes.

[release-clerk]

Release Notes Persisted

Fixed default protocol handler behavior on Windows.