fix: Updated token pricing model with context size and tier details

[ethanyhou]

Align context size calculation algorithm with Intellij:

[Copilot]

Pull request overview

Updates the Eclipse client’s understanding of token-based billing metadata so model pricing/context details align with the language server’s tiered token pricing shape and context window calculation rules.

Changes:

• Compute model context window size using token price tiers (default tier maxContext + maxOutputTokens), with fallbacks to token limits / advertised context window.
• Extend ModelInfo protocol payload with an optional contextSize field.
• Reshape token pricing protocol types to support per-tier pricing (default / longContext) and proper JSON deserialization.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/utils/ModelUtils.java	Updates model suffix context window calculation to mirror tier-aware token billing behavior.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ModelInfo.java	Adds contextSize to the model metadata record for LSP payloads.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/CopilotModel.java	Introduces tiered token pricing records (default/longContext) and batch sizing for prices.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServerConnection.java	Updates ModelInfo construction to match the new record signature.