Move common primitives to src/common/primitives/

Phase 1 of #5963: reorganize building blocks (buffer, parser, input,
data, and shared utilities) under common/primitives/. Runtime code
(services, public API, CoreTerminal, InputHandler) stays in place.

Update import paths across browser, headless, addons, and tests.
Add TypeScript path mappings so common/* aliases resolve primitives
first, then the common root.

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

addons/addon-serialize/benchmark/SerializeAddon.benchmark.ts

@@ -6,7 +6,7 @@
 import { perfContext, before, ThroughputRuntimeCase } from 'xterm-benchmark';
 
 import { spawn } from 'node-pty';
-import { Utf8ToUtf32, stringFromCodePoint } from 'common/input/TextDecoder';
+import { Utf8ToUtf32, stringFromCodePoint } from 'common/primitives/input/TextDecoder';
 import { Terminal } from 'browser/public/Terminal';
 import { SerializeAddon } from 'SerializeAddon';
 

addons/addon-serialize/benchmark/tsconfig.json

@@ -12,7 +12,8 @@
     "target": "es2021",
     "module": "nodenext",
     "paths": {
-      "common/*": ["../../../src/common/*"],
+      "common/*": ["../../../src/common/primitives/*",
+        "../../../src/common/*"],
       "browser/*": ["../../../src/browser/*"],
       "SerializeAddon": ["../src/SerializeAddon"],
       "@xterm/addon-serialize": [

addons/addon-serialize/src/SerializeAddon.ts

@@ -8,9 +8,9 @@
 import type { IBuffer, IBufferCell, IBufferRange, ITerminalAddon, Terminal } from '@xterm/xterm';
 import type { IHTMLSerializeOptions, SerializeAddon as ISerializeApi, ISerializeOptions, ISerializeRange } from '@xterm/addon-serialize';
 import { IColor } from 'common/Types';
-import { IAttributeData } from 'common/buffer/Types';
+import { IAttributeData } from 'common/primitives/buffer/Types';
 import { DEFAULT_ANSI_COLORS } from 'browser/Types';
-import { UnderlineStyle } from 'common/buffer/Constants';
+import { UnderlineStyle } from 'common/primitives/buffer/Constants';
 
 function constrain(value: number, low: number, high: number): number {
   return Math.max(low, Math.min(value, high));

addons/addon-serialize/src/tsconfig.json

@@ -12,6 +12,7 @@
     "removeComments": true,
     "paths": {
       "common/*": [
+        "../../../src/common/primitives/*",
         "../../../src/common/*"
       ],
       "browser/*": [

addons/addon-serialize/test/tsconfig.json

@@ -11,6 +11,7 @@
     "removeComments": true,
     "paths": {
       "common/*": [
+        "../../../src/common/primitives/*",
         "../../../src/common/*"
       ],
       "browser/*": [