Adapt OAuth2 implementation to Matrix Spec v1.18 (#34026)

* Adapt OAuth2 implementation to Matrix Spec v1.18

* Handle more cases of oidc->oauth

* Fix test

* Fix read back of oauth2 context

* Iterate

* Fix tests

* Discard changes to apps/web/playwright/e2e/settings/account-user-settings-tab.spec.ts

* Fix test

* Fix test

* Fix test

* Potential fix for pull request finding 'Unused variable, import, function or class'

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* Iterate

* Iterate

* Fix test

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apps/web/webpack.config.ts

@@ -252,7 +252,6 @@ export default (env: string, argv: Record<string, any>): webpack.Configuration =
                 "@matrix-org/react-sdk-module-api": getPackageRoot("@matrix-org/react-sdk-module-api"),
                 // and matrix-widget-api
                 "matrix-widget-api": getPackageRoot("matrix-widget-api"),
-                "oidc-client-ts": getPackageRoot("oidc-client-ts"),
 
                 // Make shared-components imports resolve to EW deps
                 "@vector-im/compound-web": getPackageRoot("@vector-im/compound-web", ""),