[feature]: Use jemalloc in Unix & able to control dump heap profile using http interface

[ByteYue]

PR Description

[Briefly describe your changes]
Issue Number: closes #xxx

Users can use the curl command to access the /mem_prof HTTP interface (assuming it's on port 9000) to control whether heap profiling is printed. For example:

curl -X POST -H "Content-Type: application/json" -d '{"start": true}' http://127.0.0.1:9001/mem_prof

Note Users need to ensure that jemalloc-profiling is enabled during compilation. This can be done by using make FEATURE="api/jemalloc-profiling". Also, note that this project uses tikv-jemalloc. Users need to set the following environment variables before starting the program for it to take effect:

export _RJEM_MALLOC_CONF=prof:true,lg_prof_interval:30,lg_prof_sample:21,prof_prefix:${USER_PREFIX}

(Note that the directory corresponding to this prefix must already exist).

Tested?

• Yes
• No