Change the global fetch available in local extension hosts to be the one from Electron

[chrmarti]

No description provided.

[chrmarti]

Discussion on an issue with manual redirects discovered by test failures in #228476: electron/electron#43715

Node.js chose to not follow the spec on the redirect response object which might make it difficult to use Electron's fetch as a drop-in replacement that should appear to extension the same way Node.js' fetch does.

[chrmarti]

Some headers need to be removed to not break existing use:

vscode/src/vs/platform/request/node/requestService.ts

Lines 197 to 202 in 527e41f

	// Chromium will abort the request if forbidden headers are set.
	// Ref https://source.chromium.org/chromium/chromium/src/+/main:services/network/public/cpp/header_util.cc;l=14-48;
	// for additional context.
	if (options.isChromiumNetwork) {
	req.removeHeader('Content-Length');
	}

[chrmarti]

Additional limitations: electron/electron#36733 (comment)

[chrmarti]

Putting on hold until we know how well Node.js' fetch with proxy support added works. (#228697)