Fixes #22865. Required for #21702 tests.

The basic issue is that that the current exclude flag doesn't play nicely with flags like DISCOURAGE_UPGRADABLE_NOPS + SOME_OPCODE_VERIFY.

When you have a valid TX under SOME_OPCODE_VERIFY, then the tests will try disabling that flag and it will trip over DISCOURAGE_UPGRADABLE_NOPS.

When you exclude DISCOURAGE_UPGRADABLE_NOPS, then it gets re-included when the test checks all cominations of the excluded flags being re-enabled to show failure, but then it doesn't fail when SOME_OPCODE_VERIFY is set.

To address this, we add two optional fields: 1, a list of flags to always enable; 2, a bool of if to disable the one-by-one checker.

By then testing the same vector with:

...'DISCOURAGE_UPGRADABLE_NOPS', 'NONE', true]
...'NONE', 'SOME_OPCODE_VERIFY']

we get around the one flag at a time checker.

An alternative approach, that would provide better testing coverage, would allow a more abritrary relationship checker that can be specificed by the test writer (e.g., a map of flag to implied flag) to be used during the one-by-one checker.

We cannot simply apply these rules in FillFlags/TrimFlags because if we have a transaction that should fail normally with VERIFY_SOME_OPCODE and DISCOURAGE_UPGRADABLE_OPCODES we can't support both cases.

This gap arose when implementing test vectors for BIP-119. Along the way I also discovered that, e.g., CHECKSEQUENCEVERIFY's Upgradable NOP treatment is improperly asserted as per:

                   // To provide for future soft-fork extensibility, if the
                    // operand has the disabled lock-time flag set,
                    // CHECKSEQUENCEVERIFY behaves as a NOP.
                    if ((nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) != 0)
                        break

which does not assert the proper DISCOURAGE_UPGRADABLE_NOP behavior. I beleive that lack of discouragement to be mildly worrying but not a major security concern. Fixing the testing harnesses would allow us to properly implement DISCOURAGE_UPGRADABLE_NOPS for CSV and add the corresponding test cases.