feat: enhancements to OpenTelemetry support

[evansims]

Description

This PR enhances the OpenTelemetry metrics reporting support released in 0.6.0:

• Adds TelemetryConfiguration, TelemetryMetricsConfiguration and TelemetryMetricConfiguration classes.
• Updates the Configuration class to accept a TelemetryConfiguration instance, for configuring what metrics and attributes will be used.
• Adds unit tests for all OpenTelemetry functionality.

References

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 71.27072% with 104 lines in your changes missing coverage. Please review.

Project coverage is 69.14%. Comparing base (ced2963) to head (8a41825).

Files with missing lines	Patch %	Lines
openfga_sdk/api/open_fga_api.py	37.50%	40 Missing ⚠️
openfga_sdk/sync/open_fga_api.py	37.50%	40 Missing ⚠️
openfga_sdk/telemetry/metrics.py	75.00%	10 Missing ⚠️
openfga_sdk/telemetry/attributes.py	90.14%	7 Missing ⚠️
openfga_sdk/telemetry/configuration.py	93.26%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #120      +/-   ##
==========================================
+ Coverage   68.72%   69.14%   +0.42%     
==========================================
  Files         120      121       +1     
  Lines        9772     9941     +169     
==========================================
+ Hits         6716     6874     +158     
- Misses       3056     3067      +11     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.