[Aukevanoost]

Part of #188 (point 3). Stacked on #197; review that first.

The remote builder always wrote to <outputPath>/browser. It now also accepts Angular's object form, outputPath: { base, browser? }, as build does:

• A string still writes to <outputPath>/browser, so existing configs don't move.
• { base } writes to <base>/browser, because browser defaults to 'browser' as in Angular.
• { base, browser: '' } writes directly into base.
• Other keys such as server and media are rejected by the schema: the remote builder writes neither. browser takes the same folder-name pattern as in Angular's schema, so it can't contain /.

The object form can resolve to the workspace root, for example { base: '.', browser: '' }. The old rmSync would then have deleted the whole workspace. The builder now clears its output folder with Angular's deleteOutputDir from @angular/build/private. That function refuses the workspace root itself, as in Angular. It does not guard against other folders outside the workspace: base: '..' is still accepted, as Angular accepts it. It also empties the folder rather than deleting it, so mounted or symlinked output folders keep working. As before, the folder is cleared once, when the builder starts.

Testing

• New output-path.spec.ts covers the default, a string, { base } and browser: ''.
• pnpm typecheck, pnpm test (475 passing), pnpm lint and pnpm build pass.