Add LLM Tool for Accessing Coverage Reports

[AmPaschal]

This PR adds a new tool to the coverage analyzer agent to enable it access coverage reports.
The tool splits the textcov report produced by the execution stage into its constituent functions, and allows the LLM request for the report of any specific function.
The goal is to help the coverage analyzer arrive at informed conclusions on how to increase coverage, based on existing coverage reports.

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[AmPaschal]

/gcbrun exp -n pamusuo -m vertex_ai_gemini-2-5-pro-chat -ag

[github-actions]

Requested GKE Job: ofg-pr-1187-pamusuo

JOB: https://console.cloud.google.com/kubernetes/job/us-central1-c/llm-experiment/default/ofg-pr-1187-pamusuo
REPORT: https://llm-exp.oss-fuzz.com/Result-reports/ofg-pr/2025-11-16-1187-pamusuo-comparison/index.html
BUCKET: https://console.cloud.google.com/storage/browser/oss-fuzz-gcb-experiment-run-logs/Result-reports/ofg-pr/2025-11-16-1187-pamusuo-comparison
BUCKET (GS): gs://oss-fuzz-gcb-experiment-run-logs/Result-reports/ofg-pr/2025-11-16-1187-pamusuo-comparison

[AmPaschal]

/gcbrun exp -n pamusuo -m vertex_ai_gemini-2-5-pro-chat -ag

[github-actions]

Requested GKE Job: ofg-pr-1187-pamusuo

JOB: https://console.cloud.google.com/kubernetes/job/us-central1-c/llm-experiment/default/ofg-pr-1187-pamusuo
REPORT: https://llm-exp.oss-fuzz.com/Result-reports/ofg-pr/2025-11-16-1187-pamusuo-comparison/index.html
BUCKET: https://console.cloud.google.com/storage/browser/oss-fuzz-gcb-experiment-run-logs/Result-reports/ofg-pr/2025-11-16-1187-pamusuo-comparison
BUCKET (GS): gs://oss-fuzz-gcb-experiment-run-logs/Result-reports/ofg-pr/2025-11-16-1187-pamusuo-comparison

[AmPaschal]

/gcbrun exp -n pamusuo -m vertex_ai_gemini-2-5-pro-chat -ag

[github-actions]

Requested GKE Job: ofg-pr-1187-pamusuo

JOB: https://console.cloud.google.com/kubernetes/job/us-central1-c/llm-experiment/default/ofg-pr-1187-pamusuo
REPORT: https://llm-exp.oss-fuzz.com/Result-reports/ofg-pr/2025-11-17-1187-pamusuo-comparison/index.html
BUCKET: https://console.cloud.google.com/storage/browser/oss-fuzz-gcb-experiment-run-logs/Result-reports/ofg-pr/2025-11-17-1187-pamusuo-comparison
BUCKET (GS): gs://oss-fuzz-gcb-experiment-run-logs/Result-reports/ofg-pr/2025-11-17-1187-pamusuo-comparison