Fix hover position in chat input components

[benibenj]

Copilot Generated Description: Update hover position handling in various chat input components to utilize the specified hover position options.

closes #290995

[Copilot]

Pull request overview

This PR adjusts how hovers are positioned for chat input pickers so that model/mode/session tooltips behave more stably (e.g., in the right sidebar), addressing the flickering hover behavior in the model picker.

Changes:

• Extended the generic action widget hover model (IActionListItemHover) and ActionList hover rendering to accept explicit hover position options.
• Added an optional hoverPosition to IChatInputPickerOptions and wired it through all chat input picker action items (model, mode, session target, delegation) so they can control hover placement.
• In ChatInputPart, determined the chat widget’s location (editor, sidebar left/right, panel, including maximized state) via layout/view descriptor services and used that to set a consistent hover position for picker hovers.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/browser/widget/input/sessionTargetPickerActionItem.ts	Propagates pickerOptions.hoverPosition into session type picker item hovers so their tooltip position follows the configured hover options.
src/vs/workbench/contrib/chat/browser/widget/input/modelPickerActionItem.ts	Updates the model picker’s action provider to accept IChatInputPickerOptions and applies hoverPosition to both the “Auto” entry and individual model entries.
src/vs/workbench/contrib/chat/browser/widget/input/modePickerActionItem.ts	Applies this.pickerOptions.hoverPosition to built-in and custom mode picker hover descriptors to align hover placement with the picker options.
src/vs/workbench/contrib/chat/browser/widget/input/delegationSessionPickerActionItem.ts	Ensures the “New Chat Session” additional action’s hover configuration includes this.pickerOptions.hoverPosition, keeping hover behavior consistent with other picker items.
src/vs/workbench/contrib/chat/browser/widget/input/chatInputPickerActionItem.ts	Introduces the optional hoverPosition?: IHoverPositionOptions field on IChatInputPickerOptions so chat input pickers can pass through explicit hover positioning.
src/vs/workbench/contrib/chat/browser/widget/input/chatInputPart.ts	Computes the chat widget’s location (editor, left/right sidebar, panel) and maximization state using layout and view descriptor services, derives a hoverPosition (left/right, with forcePosition: true), and passes it into all chat input picker options; also reuses this location info for the session target picker’s editor/sidebar flag.
src/vs/platform/actionWidget/browser/actionList.ts	Extends IActionListItemHover with an optional position?: IHoverPositionOptions and merges it into the hover options when showing hovers, enabling per-item control of hover placement while preserving existing defaults.