HTTP Server should not rely on File System

[phb98]

Is your enhancement proposal related to a problem? Please describe.

Currently in http2 implementation (http_server_http2.c)

 else if (detail->type == HTTP_RESOURCE_TYPE_STATIC_FS) {
			ret = handle_http2_static_fs_resource(
				(struct http_resource_detail_static_fs *)detail, frame, client);
			if (ret < 0) {
				goto error;
			}

This assumes the system have file system, which is not always true. Also http server should work without File system.
http1 implementation already has guard for this case, but this is not in http2

#if defined(CONFIG_FILE_SYSTEM)
		} else if (detail->type == HTTP_RESOURCE_TYPE_STATIC_FS) {
			ret = handle_http1_static_fs_resource(
				(struct http_resource_detail_static_fs *)detail, client);
			if (ret < 0) {
				goto error;
			}
#endif

Describe the solution you'd like

Add #ifdef guard around fs type resource, and make sure http can compile without filesystem

Additional context

CONFIG_HTTP_SERVER will include 2 http implementation of http, not sure if http2 is needed if we only need http/1.1 and below

zephyr_library_sources_ifdef(CONFIG_HTTP_SERVER http_server_core.c
						http_server_http1.c
						http_server_http2.c
						http_hpack.c
						http_huffman.c)