Activate Taproot/Tapscript on regtest (BIP 341, BIP 342)

Define a versionbits-based activation for the new consensus rules on regtest.
No activation or activation mechanism is defined for testnet or mainnet.

src/versionbitsinfo.cpp

@@ -11,4 +11,8 @@ const struct VBDeploymentInfo VersionBitsDeploymentInfo[Consensus::MAX_VERSION_B
         /*.name =*/ "testdummy",
         /*.gbt_force =*/ true,
     },
+    {
+        /*.name =*/ "taproot",
+        /*.gbt_force =*/ true,
+    },
 };