feat: update FilteredRemoteFeedbackRecords.__len__ method

[gabrielmbmb]

Description

This PR updates the __len__ method of the FilteredRemoteFeedbackRecords to return the real number of records matching the filters. To do so, we're not using any special endpoint but the list dataset records with offset=0 and limit=0.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

In a local development environment:

import random
import argilla as rg

dataset = rg.FeedbackDataset(
    fields=[
        rg.TextField(name="text")
    ],
    questions=[
        rg.TextQuestion(name="question", required=True)
    ],
    metadata_properties=[
        rg.TermsMetadataProperty(name="letters", values=["a", "b", "c"])
    ]
)

records = [rg.FeedbackRecord(
        fields={"text": "Hello world!" * random.randint(5, 50)},
        responses=[{"values": {"question": {"value": "Hello world!" * random.randint(5, 50)}}}],
        metadata={"letters": random.choice(["a", "b", "c"])}
    ) for _ in range(100000)]

dataset.add_records(records)
remote_dataset = dataset.push_to_argilla(name="random-dataset-2", workspace="gabriel")
filtered_dataset = remote_dataset.filter_by(metadata_filters=[rg.TermsMetadataFilter(name="letters", values=["a"])])
len(filtered_dataset) # ~= 33000

Checklist

• I added relevant documentation
• I followed the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[github-actions]

The URL of the deployed environment for this PR is https://argilla-quickstart-pr-3916-ki24f765kq-no.a.run.app