Add extensions support for vscode-web

[matifali]

This pull request adds support for installing extensions in vscode-web.
closes #153

• Test
• fix tests merging without tests for now.

How to test

module "vscode-web" {
  source         = "git::https://github.com/coder/modules.git//vscode-web?ref=vscode-web-extensions"
  agent_id       = coder_agent.example.id
  extensions     = ["github.copilot", "ms-python.python", "ms-toolsai.jupyter"]
  accept_license = true
}

[mafredri]

Given:

EXTENSIONS="foo,bar,baz"

I would suggest the following posix way, so we don't need to rely on bash/arrays.

Suggested change

	IFS=',' read -r -a EXTENSIONLIST <<< "$${EXTENSIONS}"
	for extension in "$${EXTENSIONLIST[@]}"; do
	if [ -z "$extension" ]; then
	continue
	fi
	printf "🧩 Installing extension $${CODE}$extension$${RESET}...\n"
	output=$($VSCODE_SERVER --install-extension "$extension" --force)
	if [ $? -ne 0 ]; then
	echo "Failed to install extension: $extension: $output"
	exit 1
	fi
	extension=
	while [ "$${extension}" != "$${EXTENSIONS}" ]; do
	extension=$${EXTENSIONS%%,*}
	EXTENSIONS=$${EXTENSIONS#*,}
	if [ -z "$${extension}" ]; then
	continue
	fi
	printf "🧩 Installing extension $${CODE}$extension$${RESET}...\n"
	output=$("$${VSCODE_SERVER}" --install-extension "$${extension}" --force)
	if [ $? -ne 0 ]; then
	echo "Failed to install extension: $${extension}: $${output}"
	exit 1
	fi

[matifali]

This section is borrowed from code-server, and I did not try to improve it as code-server is our top downloaded module and well tested. But I agree and we can update.

[matifali]

@mafredri, any second thoughts? Otherwise I should also update code-server module.

[matifali]

@mafredri I removed the tests as our modification to run commands was causing many other tests to fail.
We can add tests again in a separate PR.