Remove nes implementation so that we can implement it in a better way from scratch.

src/system/nes/mapper/nrom.zig

@@ -1,71 +0,0 @@
-const types = @import("types.zig");
-const Mirroring = types.Mirroring;
-
-const Nrom = @This();
-
-prg_16k: bool,
-mirroring_mode: Mirroring,
-
-pub fn init(
-    prg_size: usize,
-    _mirroring: Mirroring,
-) Nrom {
-    return .{
-        .prg_16k = prg_size == 0x4000,
-        .mirroring_mode = _mirroring,
-    };
-}
-
-pub fn cpuMapRead(
-    self: *const Nrom,
-    address: u16,
-) ?usize {
-    if (address < 0x8000)
-        return null;
-
-    const offset =
-        @as(usize, address) - 0x8000;
-
-    return if (self.prg_16k)
-        offset & 0x3fff
-    else
-        offset;
-}
-
-pub fn cpuWrite(
-    _: *Nrom,
-    _: u16,
-    _: u8,
-) void {
-    // NROM has no mapper registers.
-}
-
-pub fn ppuMapRead(
-    _: *const Nrom,
-    address: u16,
-) ?usize {
-    if (address >= 0x2000)
-        return null;
-
-    return address;
-}
-
-pub fn ppuMapWrite(
-    _: *const Nrom,
-    address: u16,
-) ?usize {
-    if (address >= 0x2000)
-        return null;
-
-    return address;
-}
-
-pub fn mirroring(
-    self: *const Nrom,
-) Mirroring {
-    return self.mirroring_mode;
-}
-
-pub fn irqAsserted(_: *const Nrom) bool {
-    return false;
-}