Compound RLI does not escape the char that used as separator

Compound RLI we use "," as separator. But for actual record key value, we didn't escape the separator
{code:java}
select key from hudi_metadata('customers') where type=7 order by key;
bob2@example.com$customer_id:3,customer_name:Bob, Johnson
jane@example.com$customer_id:2,customer_name:Jane, Doe
john.smith@example.com$customer_id:1,customer_name:John Smith
john@example.com$customer_id:1,customer_name:John, Smith {code}
I didn't find correctness issue so far based on my very limited understanding of compound RLI. I'm scared by the fact that this behavior is not compliant with the basic design principles of handling strings which makes the logic very shaky IMO.

Extending this to all other indices. We should think about this as well.

if an index could come with some compound fashion + no separator escaping in the value content, we must make sure we
* never try to split The key based on the separator
* never do prefix lookup (compound keys has 2 keys, we prefix lookup on the first key)

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-9738
- Type: Bug
- Fix version(s):
- 1.1.0