Fix remap_column_names (explodinggradients#140)

When I try to do the following, I got error:

```python
ds = Dataset.from_dict(
    {
        "question": ["question"],
        "answer": ["answer"],
        "contexts": [["context"]],
    }
)

from ragas import evaluate
from ragas.metrics import Faithfulness

evaluate(dataset =ds, metrics=[Faithfulness(batch_size=1)])
```

```
KeyError: "Column ground_truths not in the dataset. Current columns in the dataset: ['question', 'answer', 'contexts']"
```
But `ground_truths ` is not needed for `Faithfulness` .

This PR is to fix it.

fix: linting issues (explodinggradients#138)

Improve context relevancy (explodinggradients#112)

## What
Improve context relevancy prompt 

## Why
LLM has trouble doing candidate sentence extraction. The current prompt
has caused issues where context relevancy becomes zero due to a
suboptimal prompt. This prompt is tested on data from Arxiv,
StackOverflow, etc.

fixes: explodinggradients#109

Context Recall (explodinggradients#96)

## What
Context recall estimation using annotated answers as ground truth

## Why
Context recall was a highly requested feature, as it is one of the main
pain points where pipeline error occurs in RAG systems

## How
Introduced a simple paradigm similar to faithfulness

---------

Co-authored-by: jjmachan <[email protected]>

docs: notebook for langsmith integration (explodinggradients#85)

chore: added an e2e test in Makefile (explodinggradients#76)

fix: n_swapped check for generate (explodinggradients#73)

docs: notebook guide for custom llm (explodinggradients#68)

chore: renamed files and added tqdm (explodinggradients#65)

fix: Result output (explodinggradients#57)