* Added global http client
* Added Do func for global http client
* Changed the code to use the global http client
* Fix http client in volume uploader
* Fixed pkg name
* Fixed http util funcs
* Fixed http client for bench_filer_upload
* Fixed http client for stress_filer_upload
* Fixed http client for filer_server_handlers_proxy
* Fixed http client for command_fs_merge_volumes
* Fixed http client for command_fs_merge_volumes and command_volume_fsck
* Fixed http client for s3api_server
* Added init global client for main funcs
* Rename global_client to client
* Changed:
- fixed NewHttpClient;
- added CheckIsHttpsClientEnabled func
- updated security.toml in scaffold
* Reduce the visibility of some functions in the util/http/client pkg
* Added the loadSecurityConfig function
* Use util.LoadSecurityConfiguration() in NewHttpClient func
The mime type is always the value passed in.
Compress or not depends on the content detection, file name extension, and compression ratio.
If the content is already compressed, need to know the content size.
