refactor: Add paychan namespace and update related tests (#5840)

This change adds a paychan namespace to the TestHelpers and implementation files, improving organization and clarity. Additionally, it updates the AMM test to use the new `paychan::create` function for payment channel creation.

Co-authored-by: Bart Thomee <11445373+bthomee@users.noreply.github.com>

src/test/app/AMM_test.cpp

@@ -3666,7 +3666,7 @@ private:
             auto const settleDelay = 100s;
             NetClock::time_point const cancelAfter =
                 env.current()->info().parentCloseTime + 200s;
-            env(create(
+            env(paychan::create(
                     carol,
                     ammAlice.ammAccount(),
                     XRP(1'000),

src/test/app/PayChan_test.cpp

@@ -31,6 +31,8 @@
 
 namespace ripple {
 namespace test {
+using namespace jtx::paychan;
+
 struct PayChan_test : public beast::unit_test::suite
 {
     FeatureBitset const disallowIncoming{featureDisallowIncoming};

src/test/jtx/TestHelpers.h

@@ -502,6 +502,7 @@ expectLedgerEntryRoot(
 
 /* Payment Channel */
 /******************************************************************************/
+namespace paychan {
 
 Json::Value
 create(
@@ -561,6 +562,8 @@ channelBalance(ReadView const& view, uint256 const& chan);
 bool
 channelExists(ReadView const& view, uint256 const& chan);
 
+}  // namespace paychan
+
 /* Crossing Limits */
 /******************************************************************************/
 

src/test/jtx/impl/TestHelpers.cpp

@@ -237,6 +237,8 @@ expectLedgerEntryRoot(
 
 /* Payment Channel */
 /******************************************************************************/
+namespace paychan {
+
 Json::Value
 create(
     AccountID const& account,
@@ -328,6 +330,8 @@ channelExists(ReadView const& view, uint256 const& chan)
     return bool(slep);
 }
 
+}  // namespace paychan
+
 /* Crossing Limits */
 /******************************************************************************/