update document partially by specified entity

[puppylpg]

Now if we wanna update a document, a UpdateQuery must be constructed manually, but this is a little unnecessary. Especially for the condation that:

1. get a document from index;
2. update some field of the document;
3. write the doc back;

Problems are:

1. if write the doc back using save(ENTITY), values of fields which are unmapped in the entity will be discarded;
2. if write the doc back using update(UpdateQuery, IndexCoordinates), a UpdateQuery and a IndexCoordinates must be constructed manually;

So i think update(T entity) is necessary, and spring-data-elasticsearch can construct the UpdateQuery and IndexCoordinates automatically, which is very handy.

[sothawo]

Have to reopen; I noticed, that the PR was targeting the wrong branch. Can you please create a new PR with the changes - then with what I commented and target the main branch?

[puppylpg]

Sorry for the wrong branch, and i'll polish and reopen a PR for main

[puppylpg]

submited: #2310