sched: programmable: add bpf_sched_tg_tag_of helper function

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5KUFB


CVE: NA

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This helper function read the task group tag for a task.
The bpf prog obtains the tags to detect different workloads.

Signed-off-by: Ren Zhijie <renzhijie2@huawei.com>
Signed-off-by: Chen Hui <judy.chenhui@huawei.com>
Signed-off-by: Hui Tang <tanghui20@huawei.com>