Remove the L from unevaluated string literals. (#4609)

This resolves build failures on macOS 15 "Sequoia" / XCode Command Line Tools 16 detected while attempting to update vcpkg's build and test lab: microsoft/vcpkg#41307

Example:

```
/Users/vcpkg/Data/b/msquic/src/v2.4.5-9d07a67b94.clean/src/core/quicdef.h:243:66: error: encoding prefix 'L' on an unevaluated string literal has no effect [-Werror,-Winvalid-unevaluated-string]
  243 | CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_ALLOC_SIZE), L"Must be power of two");
      |                                                                  ^
```

src/core/mtu_discovery.c

@@ -34,8 +34,8 @@
 #include "mtu_discovery.c.clog.h"
 #endif
 
-CXPLAT_STATIC_ASSERT(CXPLAT_MAX_MTU >= QUIC_DPLPMTUD_DEFAULT_MAX_MTU, L"Default max must not be more than max");
-CXPLAT_STATIC_ASSERT(QUIC_DPLPMTUD_MIN_MTU <= QUIC_DPLPMTUD_DEFAULT_MIN_MTU, L"Default min must not be less than min");
+CXPLAT_STATIC_ASSERT(CXPLAT_MAX_MTU >= QUIC_DPLPMTUD_DEFAULT_MAX_MTU, "Default max must not be more than max");
+CXPLAT_STATIC_ASSERT(QUIC_DPLPMTUD_MIN_MTU <= QUIC_DPLPMTUD_DEFAULT_MIN_MTU, "Default min must not be less than min");
 
 _IRQL_requires_max_(PASSIVE_LEVEL)
 static

src/core/packet_builder.h

@@ -158,7 +158,7 @@ typedef struct QUIC_PACKET_BUILDER {
 
 CXPLAT_STATIC_ASSERT(
     sizeof(QUIC_PACKET_BUILDER) < 1024,
-    L"Packet builder should be small enough to fit on the stack.");
+    "Packet builder should be small enough to fit on the stack.");
 
 //
 // Initializes the packet builder for general use.

src/core/quicdef.h

@@ -240,10 +240,10 @@ typedef struct QUIC_RX_PACKET QUIC_RX_PACKET;
 #define QUIC_MAX_RANGE_ACK_PACKETS              0x800       // 2048
 #define QUIC_MAX_RANGE_DECODE_ACKS              0x1000      // 4096
 
-CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_ALLOC_SIZE), L"Must be power of two");
-CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_DUPLICATE_PACKETS), L"Must be power of two");
-CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_ACK_PACKETS), L"Must be power of two");
-CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_DECODE_ACKS), L"Must be power of two");
+CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_ALLOC_SIZE), "Must be power of two");
+CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_DUPLICATE_PACKETS), "Must be power of two");
+CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_ACK_PACKETS), "Must be power of two");
+CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(QUIC_MAX_RANGE_DECODE_ACKS), "Must be power of two");
 
 //
 // Minimum MTU allowed to be configured. Must be able to fit a
@@ -300,7 +300,7 @@ CXPLAT_STATIC_ASSERT(QUIC_INITIAL_PACKET_LENGTH >= QUIC_MIN_INITIAL_PACKET_LENGT
 
 CXPLAT_STATIC_ASSERT(
     QUIC_DEFAULT_DISCONNECT_TIMEOUT <= QUIC_MAX_DISCONNECT_TIMEOUT,
-    L"Default disconnect timeout should always be less than max");
+    "Default disconnect timeout should always be less than max");
 
 //
 // The default connection idle timeout (in milliseconds).

src/core/range.h

@@ -21,7 +21,7 @@ typedef struct QUIC_SUBRANGE {
 
 } QUIC_SUBRANGE;
 
-CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(sizeof(QUIC_SUBRANGE)), L"Must be power of two");
+CXPLAT_STATIC_ASSERT(IS_POWER_OF_TWO(sizeof(QUIC_SUBRANGE)), "Must be power of two");
 
 typedef struct QUIC_RANGE_SEARCH_KEY {