Use Post for Streaming Endpoints

[NarekA]

Http streaming breaks when the input doc schema has fields which are not str, int, or float. This includes dicts, bools, and nested objects (See Issue 6090). In addition it caps the input size to 2000 characters (Much less when you factor in URL encoding)

This PR changes the get endpoints to post endpoints. Not sure if we want to keep the get endpoints for backwards compatibility.

Goals:

• resolves Issue 6090
• [x] check and update documentation. See guide and ask the team.

[codecov[bot]]

Codecov Report

Attention: 27 lines in your changes are missing coverage. Please review.

Comparison is base (2c3d7d3) 76.36% compared to head (ab254e5) 74.65%. Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6091 +/- ## ========================================== - Coverage 76.36% 74.65% -1.72% ========================================== Files 145 145 Lines 14007 14024 +17 ========================================== - Hits 10697 10469 -228 - Misses 3310 3555 +245 ``` | [Flag](https://app.codecov.io/gh/jina-ai/jina/pull/6091/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai) | Coverage Δ | | |---|---|---| | [jina](https://app.codecov.io/gh/jina-ai/jina/pull/6091/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai) | `74.65% <6.89%> (-1.72%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/jina-ai/jina/pull/6091?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai) | Coverage Δ | | |---|---|---| | [jina/\_\_init\_\_.py](https://app.codecov.io/gh/jina-ai/jina/pull/6091?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai#diff-amluYS9fX2luaXRfXy5weQ==) | `56.00% <100.00%> (ø)` | | | [jina/clients/base/helper.py](https://app.codecov.io/gh/jina-ai/jina/pull/6091?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai#diff-amluYS9jbGllbnRzL2Jhc2UvaGVscGVyLnB5) | `79.06% <0.00%> (-6.08%)` | :arrow_down: | | [...ve/runtimes/gateway/http\_fastapi\_app\_docarrayv2.py](https://app.codecov.io/gh/jina-ai/jina/pull/6091?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai#diff-amluYS9zZXJ2ZS9ydW50aW1lcy9nYXRld2F5L2h0dHBfZmFzdGFwaV9hcHBfZG9jYXJyYXl2Mi5weQ==) | `0.00% <0.00%> (ø)` | | | [jina/serve/runtimes/worker/http\_fastapi\_app.py](https://app.codecov.io/gh/jina-ai/jina/pull/6091?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai#diff-amluYS9zZXJ2ZS9ydW50aW1lcy93b3JrZXIvaHR0cF9mYXN0YXBpX2FwcC5weQ==) | `60.16% <7.14%> (-21.99%)` | :arrow_down: | ... and [23 files with indirect coverage changes](https://app.codecov.io/gh/jina-ai/jina/pull/6091/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jina-ai)

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[NarekA]

Added the get endpoints back, and I will add some tests for the post endpoint. This feature will also align us with openai since they are using streaming on post endpoints too.

[NarekA]

@JoanFM @alaeddine-13 created a new PR that follows conventions, working on adding tests too.