docs: optimize time picker demo api docs

[kagol]

PR

主要优化点：

1. size-small/size-medium/size-mini 三个demo合并成一个 size.vue，时间选择和时间范围选择的尺寸
2. clearable/clear-icon 合并成一个 clearable.vue，隐藏清除按钮和修改清除按钮图标
3. format/date/time-low/time-upp 合并成一个 format.vue，输入框显示的格式、下拉框显示的格式、绑定值的格式
4. disabled/picker-options 合并成 disabled.vue，全局禁用和部分禁用
5. basic-usage/arrow-control 合并成 basic-usage.vue，支持滚动和箭头点击两种交互方式
6. 增加 placeholder 的 demo，之前混在别的demo里不太合理
7. 移除跟当前demo无关的属性，每个demo聚焦展示某一个特性
8. 增加宽度样式
9. api按照首字母字典顺序排序

TimePicker 文档链接

PR Checklist

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• The commit message follows our Commit Message Guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

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