Added ReferencesPriv to DB and Table level, see tidb issue 26703 (#1304)

[ti-chi-bot]

This is an automated cherry-pick of #1304

What problem does this PR solve?

Parser related fix for pingcap/tidb#26703 (ReferencesPriv needs to be on both DB/Schema and Table level).

What is changed and how it works?

In MySQL, the REFERENCES privilege can be on both DB and Table level, the Parser definition AllDBPrivs and AllTablePrivs did not include ReferencesPriv which made TiDB fail when checking it.

Check List

Tests

• Manual test (add detailed scripts or steps below)
  • Built TiDB with go.mod change replace github.com/pingcap/parser => ../parser to build tidb-server with the locally changed parser repository
  • Tested CREATE USER r;, CREATE SCHEMA reftest;, USE reftest, CREATE TABLE t (a int);, GRANT REFERENCES ON reftest.* TO r; and GRANT REFERENCES ON reftest.t TO r; which did succeed, just like in MySQL.

Code changes

• Has exported variable/fields change: AllDBPrivs and AllTablePrivs

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• kennytm
• tangenta

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