Add --position argument to wt new-tab command

[Jotanune]

Summary of the Pull Request

Adds a --position argument to the wt new-tab subcommand, allowing users to control where new tabs are inserted without changing the global newTabPosition setting.

This addresses #14687.

References and Relevant Issues

Closes #14687

Detailed Description of the Pull Request / Additional comments

Changes:

• ActionArgs.idl / ActionArgs.h: Added Position property (IReference<NewTabPosition>) to NewTabArgs, with full JSON serialization, equality, copy, and hash support.
• GlobalAppSettings.idl / ActionArgs.idl: Moved NewTabPosition enum from GlobalAppSettings.idl to ActionArgs.idl to avoid circular IDL import dependencies. The enum remains accessible to GlobalAppSettings through the transitive import chain.
• AppCommandlineArgs.h/.cpp: Registered --position CLI option in _buildNewTabParser(), accepting afterCurrentTab and afterLastTab string values.
• AppActionHandlers.cpp: Modified _HandleNewTab to extract the position from NewTabArgs, calculate the insert index, and pass it to _OpenNewTab.
• TerminalPage.h / TabManagement.cpp: Updated _OpenNewTab signature to accept an insertPosition parameter, forwarded to _CreateNewTabFromPane.
• Resources.resw: Added CmdTabPositionArgDesc localization resource string.
• profiles.schema.json: Added position property to NewTabAction schema.
• CommandlineTest.cpp: Added ParseNewTabWithPosition test method with 4 test cases.

Usage:

# Open a new tab after the current tab
wt new-tab --position afterCurrentTab

# Open a new tab at the end (default)
wt new-tab --position afterLastTab

# Combined with other arguments
wt new-tab --position afterCurrentTab --profile cmd

Validation Steps Performed

• Code compiles without errors (x64 Debug)
• All modified files verified for correctness
• Unit test ParseNewTabWithPosition added with 4 test cases
• JSON schema updated

[Jotanune]

@Jotanune please read the following Contributor License Agreement(CLA). If you agree with the CLA, please reply with the following information.

@microsoft-github-policy-service agree [company="{your company}"]

Options:

• (default - no company specified) I have sole ownership of intellectual property rights to my Submissions and I am not making Submissions in the course of work for my employer.

@microsoft-github-policy-service agree

• (when company given) I am making Submissions in the course of work for my employer (or my employer has intellectual property rights in my Submissions by contract or applicable law). I have permission from my employer to make Submissions and enter into this Agreement on behalf of my employer. By signing below, the defined term “You” includes me and my employer.

@microsoft-github-policy-service agree company="Microsoft"

Contributor License Agreement

@microsoft-github-policy-service agree

[KalleOlaviNiemitalo]

Does this get the index of the tab in which the wt command was run? From the function name, I'd assume it doesn't.

[Jotanune]

You are absolutely right. _GetFocusedTabIndex() grabs the currently active tab, which completely fails the sleep 10 edge-case if the user switches tabs during execution. I'll look into the proper way to resolve the origin tab and update the PR.

[DHowett]

I'm gonna tell you it's not possible in the general case to do so. :)

[Jotanune]

Haha, thanks for the reality check @DHowett that definitely saves me from going down an impossible rabbit hole with WT_SESSION and IPC messages. 😅
​Given that tracking the exact originating tab asynchronously isn't technically feasible in the general architecture, would using the currently focused tab (as currently implemented via _GetFocusedTabIndex()) be an acceptable compromise for this feature? It solves the immediate UX need for synchronous commands like your vspwsh alias mentioned in the issue, even if it falls short on the sleep 10 edge-case.
​Let me know if you guys are happy with this trade-off, or if I should add a specific comment in the code/docs about this limitation.