Insiders build of the extension depends on unpackaged files

[patrys]

The nightly build tries to import ../test/constants from client/extension.js but the client/test dir is not part of the distribution.

[DonJayamanne]

@MikhailArkhipov Please could you look into this. Should be a simple fix.
@patrys Thanks for pointing this out.

[MikhailArkhipov]

Yeah, it imports IS_ANALYSIS_ENGINE_TEST