Improve code snipper HTTP

Describe the bug

When the HTTP code snippet is generated, it is generated with the first letter in uppercase and the format should be the same as in the header. A difference if the type CURL is selected maintains the correct format.

To Reproduce
Execute a example of request.
Clic in code snipper {}.
In code select HTTP.

Expected behavior
The expected behavior is to keep the same format as the header, as is done in the CURL.

Platform:

OS: Windows 10
vscode version: 1.66.2
extension version: 1.18.7

Example:

Screenshot type http:

Screenshot type curl:

best regards

首先重现 issue 中 request-snippet 的步骤，并比较生成的 HTTP 和 CURL 输出，重点关注大小写和格式。HTTP 代码片段保持与其标头相同的格式，并与现有的 CURL 行为一致时，这项工作就完成了。