Add issue templates for bugs, features, docs, and questions

[serengil]

Description

This PR adds GitHub issue templates to help users submit issues with a standard format.

The following templates are included:

• Bug report – for reporting bugs in a structured way
• Feature request – for suggesting new features
• Documentation – for documenting improvements or corrections
• Question – for asking questions about the project

Additionally, labels will be automatically assigned based on the selected template, helping maintain consistency and streamline issue triage.

Once, this PR is merged, then issue tracker of neo4j-graphrag-python package will be looking like this.

Type of Change

• New feature
• Bug fix
• Breaking change
• Documentation update
• Project configuration change

Complexity

Doesn't affect anything in the code base, it's all about issue tracker

Complexity:

How Has This Been Tested?

• Unit tests
• E2E tests
• Manual tests

Checklist

The following requirements should have been met (depending on the changes in the branch):

• Documentation has been updated
• Unit tests have been updated
• E2E tests have been updated
• Examples have been updated
• New files have copyright header
• CLA (https://neo4j.com/developer/cla/) has been signed
• CHANGELOG.md updated if appropriate