Correct the registry domain separator and refactor test suite

* Test internal variable initialization in registry constructor tests
* Improvements to domain separator test
* Improvements to the RegisteryKeys tests
* Naming improvements to registerKeysOnBehalf tests
* Update test imports and remove duplicated import
* Refactor signature test helpers for test simplicity
* Simplify mock contract for ERC1271 signatures
* Remove redundant test and add missing ones for register on behalf
* Minor cleanup to increment nonce test
* Update the EIP712Domain separator to match the spec
* Simplify Announcer test names
* Use `vm.expectRevert("")` instead of `vm.expectRevert()`

src/ERC6538Registry.sol

@@ -131,7 +131,7 @@ contract ERC6538Registry {
     return keccak256(
       abi.encode(
         keccak256(
-          "EIP712Domain(string name,string version,uint256 chainId,address registryContract)"
+          "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
         ),
         keccak256("ERC6538Registry"),
         keccak256("1.0"),

test/ERC5564Announcer.t.sol

@@ -19,7 +19,7 @@ contract ERC5564AnnouncerTest is Test, Deploy {
 }
 
 contract Announce is ERC5564AnnouncerTest {
-  function testFuzz_EmitsAnnouncementEventForAnyCaller(
+  function testFuzz_EmitsAnnouncementEvent(
     uint256 schemeId,
     address stealthAddress,
     address caller,
@@ -38,7 +38,7 @@ contract Announce is ERC5564AnnouncerTest {
   /// forge-config: default.fuzz.runs = 1
   /// forge-config: ci.fuzz.runs = 1
   /// forge-config: lite.fuzz.runs = 1
-  function testFuzz_AlwaysSucceedsForAnyCallerThatCallsTheAnnounceFunction(
+  function testFuzz_AlwaysSucceeds(
     uint256 schemeId,
     address stealthAddress,
     address caller,