Post-merge-review: Fix template-require-input-label mustache branch: apply strict-mode guard

[johanrd]

What's broken on master

template-require-input-label handles Ember's built-in Input/Textarea in two separate branches:

1. Mustache form (GlimmerMustacheStatement) — for {{input}} / {{textarea}}.
2. Element form (GlimmerElementNode) — for <Input> / <Textarea>.

Two issues on master:

• The mustache branch runs in both HBS and strict mode (.gjs/.gts). But {{input}}/{{textarea}} in a .gjs/.gts are user-imported JS bindings, unrelated to the classic Ember helpers — so the rule should not treat them as form controls requiring a label.
• The element branch matches <Input> / <Textarea> by bare tag name. In strict mode this both false-positives on user-authored <Input> components (anything locally named Input gets flagged) and false-negatives on renamed framework imports like import { Input as Field } from '@ember/component'; <Field />.

Fix

• Mustache branch: gate with isStrictMode so the check only runs in HBS, where {{input}}/{{textarea}} are unambiguously the classic helpers.
• Element branch: in strict mode, track ImportDeclaration specifiers from '@ember/component' (for Input and Textarea, supporting renames) and only treat a tag as the built-in if it resolves to a tracked import. In HBS, keep the existing bare-name match. Same pattern as template-no-builtin-form-components.

Net effect in strict mode:

Code	Before	After
<Input /> with no @ember/component import	not flagged (skipped)	not flagged (user component)
import { Input } from '@ember/component'; <Input />	not flagged (skipped)	flagged (no label)
import { Textarea as TA } from '@ember/component'; <TA />	not flagged (bare-name miss)	flagged (no label)
{{input}} in .gjs	flagged (wrong)	not flagged

HBS behavior is unchanged.

Test plan

• pnpm vitest run tests/lib/rules/template-require-input-label.js — 113 tests pass.
• Added invalid GJS test: import { Input } from '@ember/component'; <template><Input /></template>.
• Added invalid GTS test for renamed import: import { Textarea as TA } from '@ember/component'; <template><TA /></template>.
• Added valid GJS test: <Input /> in a .gjs file with no @ember/component import (user-authored).
• Added valid GJS test: import { Input } from '@ember/component'; <template><label>Name <Input /></label></template>.
• Existing HBS and strict-mode mustache tests still pass.