refactor(InputsElementFormSupport): add file extension to import

[MarcusNotheis]

Without the .js file extension, projects building in ESM mode will fail due do an import error:

node_modules/@ui5/webcomponents/dist/features/InputElementsFormSupport.d.ts:1:29 - error TS2307: Cannot find module '@ui5/webcomponents-base/dist/UI5Element' or its corresponding type declarations.

1 import type UI5Element from "@ui5/webcomponents-base/dist/UI5Element";
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