Add filtering of pipelines by name to public pipelines API

What does this MR do and why?

Describe in detail what your merge request does and why.

• Add filtering of pipelines by name to PipelinesFinder.
• Add name to Entities::Ci::PipelineBasic.
• Add an index on pipeline_id, lower(name) to ci_pipeline_metadata, and remove the existing index.
• Add PipelineMetadata to preloaders of APIs that use Entities::Ci::PipelineBasic.

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MR acceptance checklist

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