The patch addresses #3745.
The cache should return the exact amount of data requested by the buffer.
By construction of the cache it is always all requested data range
or we have error happening.
The old use of minsize miscalculate the requested data size,
if non zero offset is requested.
* 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