[fix](sql-functions) provide setup data for the EXPORT_SET table example

[boluor]

The EXPORT_SET page shows SELECT ... FROM test_export_set examples with an expected result, but never defines test_export_set. As written these examples cannot be run or reproduced — a reader who copies them gets Table [...] does not exist.

This PR adds the missing CREATE TABLE + INSERT, carried in a standard HTML comment (<!-- setup-sql ... -->) just before the example. Because it is an HTML comment, the rendered page is unchanged and no documented expected output is modified.

The table contents were reverse-derived from the printed input table and verified end-to-end on version-4.x (a 4.1.1 cluster) and dev/current (a master build): both the input table and the EXPORT_SET(...) results match the documented output exactly, including the row whose separator is the literal |123|.

The page exists only in the dev/current and version-4.x trees; updated in EN + ZH (4 files). No ja-source changes.

Note: a separate, pre-existing inconsistency on this page — one example whose SQL selects a single column while its output table shows six (bits | on | off | sep | num_of_b | ans) — is not addressed here; it is tracked in #3879 so the SQL/output correction can be reviewed on its own.