Add Megaservice support for MMRAG VideoRAGQnA usecase

[BaoHuiling]

Description

Add support for upcoming MMRAG VideoRAGQnA usecase in GenAIExamples, the PR is under developing.
Also fix bug founded

Issues

List the issue or RFC link this PR is working on. If there is no such link, please mark it as n/a.

Type of change

List the type of change like below. Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would break existing design and interface)
• Others (enhancement, documentation, validation, etc.)

Dependencies

N/A

Tests

tests/cores/mega/test_service_orchestrator_with_videoragqnagateway.py

[BaoHuiling]

@tileintel Hello Tiep, I raise this PR for my megaservice. It's independent from you megaservice, just want to let you know. Thanks

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 15 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
comps/cores/mega/gateway.py	21.05%	15 Missing ⚠️

Files with missing lines	Coverage Δ
comps/cores/mega/constants.py	98.24% <100.00%> (+0.03%)	⬆️
comps/cores/mega/gateway.py	35.18% <21.05%> (-0.72%)	⬇️

... and 2 files with indirect coverage changes

[BaoHuiling]

@chensuyue Hello Suyue, does this change requires additional test script/function? If yes, where to add?

[BaoHuiling]

@ftian1 @chensuyue @ZePan110 Hello, anyone has comment on this one?

[hshen14]

@chensuyue Hello Suyue, does this change requires additional test script/function? If yes, where to add?

please add unit tests to improve the code coverage.

[BaoHuiling]

@chensuyue Hello Suyue, does this change requires additional test script/function? If yes, where to add?

please add unit tests to improve the code coverage.

No problem. Where should I add it, or do you have any references? I didn't saw the unit test for other gateways.

[chensuyue]

@chensuyue Hello Suyue, does this change requires additional test script/function? If yes, where to add?

please add unit tests to improve the code coverage.

No problem. Where should I add it, or do you have any references? I didn't saw the unit test for other gateways.

https://github.com/opea-project/GenAIComps/tree/main/tests/cores/mega

[BaoHuiling]

Test script added at tests/cores/mega/test_service_orchestrator_with_videoragqnagateway.py.
Would you help to review and merge the code? @lvliang-intel @ftian1 @hshen14 Thanks a lot

[BaoHuiling]

Per Chang, Hanwen's requirement, update related code structure based on PR #625

[BaoHuiling]

Rebase the changes per @letonghan 's request, will wait until #625 is merged

[BaoHuiling]

Hello, @XuhuiRen @kevinintel the CI is all passed, could you help to merge the code? We have another PR in example repo depending on this, I’m afraid we don’t have enough time to wait until the Reorg changes merged.