refactor(postgres) improve postgres code base (#20808)

Co-authored-by: cirospaciari <6379399+cirospaciari@users.noreply.github.com>

src/sql/postgres/protocol/StackReader.zig

@@ -0,0 +1,66 @@
+buffer: []const u8 = "",
+offset: *usize,
+message_start: *usize,
+
+pub fn markMessageStart(this: @This()) void {
+    this.message_start.* = this.offset.*;
+}
+
+pub fn ensureLength(this: @This(), length: usize) bool {
+    return this.buffer.len >= (this.offset.* + length);
+}
+
+pub fn init(buffer: []const u8, offset: *usize, message_start: *usize) NewReader(StackReader) {
+    return .{
+        .wrapped = .{
+            .buffer = buffer,
+            .offset = offset,
+            .message_start = message_start,
+        },
+    };
+}
+
+pub fn peek(this: StackReader) []const u8 {
+    return this.buffer[this.offset.*..];
+}
+pub fn skip(this: StackReader, count: usize) void {
+    if (this.offset.* + count > this.buffer.len) {
+        this.offset.* = this.buffer.len;
+        return;
+    }
+
+    this.offset.* += count;
+}
+pub fn ensureCapacity(this: StackReader, count: usize) bool {
+    return this.buffer.len >= (this.offset.* + count);
+}
+pub fn read(this: StackReader, count: usize) AnyPostgresError!Data {
+    const offset = this.offset.*;
+    if (!this.ensureCapacity(count)) {
+        return error.ShortRead;
+    }
+
+    this.skip(count);
+    return Data{
+        .temporary = this.buffer[offset..this.offset.*],
+    };
+}
+pub fn readZ(this: StackReader) AnyPostgresError!Data {
+    const remaining = this.peek();
+    if (bun.strings.indexOfChar(remaining, 0)) |zero| {
+        this.skip(zero + 1);
+        return Data{
+            .temporary = remaining[0..zero],
+        };
+    }
+
+    return error.ShortRead;
+}
+
+// @sortImports
+
+const StackReader = @This();
+const bun = @import("bun");
+const AnyPostgresError = @import("../AnyPostgresError.zig").AnyPostgresError;
+const Data = @import("../Data.zig").Data;
+const NewReader = @import("./NewReader.zig").NewReader;