Rename the field and scalar modules

Suggested by @kubkon

lib/std/crypto.zig

@@ -63,8 +63,8 @@ test "crypto" {
     _ = @import("crypto/25519/curve25519.zig");
     _ = @import("crypto/25519/ed25519.zig");
     _ = @import("crypto/25519/edwards25519.zig");
-    _ = @import("crypto/25519/field25519.zig");
-    _ = @import("crypto/25519/scalar25519.zig");
+    _ = @import("crypto/25519/field.zig");
+    _ = @import("crypto/25519/scalar.zig");
     _ = @import("crypto/25519/x25519.zig");
     _ = @import("crypto/25519/ristretto255.zig");
 }

lib/std/crypto/25519/curve25519.zig

@@ -3,9 +3,9 @@ const std = @import("std");
 /// Group operations over Curve25519.
 pub const Curve25519 = struct {
     /// The underlying prime field.
-    pub const Fe = @import("field25519.zig").Fe;
+    pub const Fe = @import("field.zig").Fe;
     /// Field arithmetic mod the order of the main subgroup.
-    pub const scalar = @import("scalar25519.zig");
+    pub const scalar = @import("scalar.zig");
 
     x: Fe,
 

lib/std/crypto/25519/edwards25519.zig

@@ -4,9 +4,9 @@ const fmt = std.fmt;
 /// Group operations over Edwards25519.
 pub const Edwards25519 = struct {
     /// The underlying prime field.
-    pub const Fe = @import("field25519.zig").Fe;
+    pub const Fe = @import("field.zig").Fe;
     /// Field arithmetic mod the order of the main subgroup.
-    pub const scalar = @import("scalar25519.zig");
+    pub const scalar = @import("scalar.zig");
 
     x: Fe,
     y: Fe,

lib/std/crypto/25519/scalar.zig

@@ -174,7 +174,7 @@ test "non-canonical scalar25519" {
     std.testing.expectError(error.NonCanonical, rejectNonCanonical(too_targe));
 }
 
-test "mulAdd overflow check" {
+test "scalar25519 mulAdd overflow check" {
     const a: [32]u8 = [_]u8{0xff} ** 32;
     const b: [32]u8 = [_]u8{0xff} ** 32;
     const c: [32]u8 = [_]u8{0xff} ** 32;