Update Portal Component to Remove Legacy Context API Usage

[kmpeeduwee]

Description:
The Blueprint5.Portal component currently relies on the legacy contextTypes API, which was removed in React 19. This results in compatibility issues with React 19 and newer. The component should be updated to use the modern React.createContext() API alongside React.useContext() for better compatibility and future-proofing.

Error Message:
Blueprint5.Portal uses the legacy contextTypes API which was removed in React 19. Use React.createContext() with React.useContext() instead. (https://react.dev/link/legacy-context) Component Stack: Portal portal.tsx:82 Overlay2 overlay2.tsx:98 Popper Popper.js:16 Manager Manager.js:5 Popover2 chunk-VCJ3HYCT.js:19285 div unknown:0 ConnectFunction Redux div unknown:0 Router chunk-W3HZJLUQ.mjs:4984 HistoryRouter chunk-W3HZJLUQ.mjs:7117 Provider Redux

Steps to Reproduce:

1. Use Blueprint5 with React 19.
2. Render any component that depends on Portal (e.g., Popover2, Overlay2).
3. Observe the error in the console.

Expected Behavior:
The Portal component should function without errors by leveraging the modern React context API, ensuring compatibility with React 19 and above.

Proposed Solution:

• Refactor the Portal component to replace the usage of contextTypes with React.createContext() and React.useContext().
• Ensure compatibility with React 18 and React 19.

Additional Context:

• React Legacy Context Documentation
• The issue has been observed in components that rely on Portal, such as Overlay2 and Popover2.

Impact:
This issue affects users upgrading to React 19, potentially breaking applications that depend on the Portal component.

[kmpeeduwee]

I added a pull reguest - #7137

[bppdddqqqq]

The pull request does fix the issue, but it won't fully fix up React 19 support. See #7139