[COMPILER/FEATURE] Support rt_packed

[GuEe-GUI]

拉取/合并请求描述：(PR description)

[

Origin:
__ARMCC_VERSION:

• https://smtp.keil.com/support/man/docs/armcc/armcc_chr1359124980173.htm

__IAR_SYSTEMS_ICC__:

• Not Found

__GNUC__:

• https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute

__ADSPBLACKFIN__:

• Not Found

_MSC_VER:

• https://learn.microsoft.com/en-us/cpp/preprocessor/pack?view=msvc-170

__TI_COMPILER_VERSION__:

• https://software-dl.ti.com/codegen/docs/tiarmclang/rel1_3_0_LTS/migration_guide/migrating_c_and_cpp_source/pragmas_and_attributes.html

__TASKING__:

• https://resources.tasking.com/sites/default/files/2021-02/TASKING_Alignment%20Requirements%20Restrictions_WEB.pdf

Usage:

rt_packed(struct object1
{
    int dword;
    char byte;
});
typedef struct object1 object1;

rt_packed(struct object2
{
    int dword;
    char byte;
});

]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting 等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/workflows/bsp_buildings.yml 详细请参考链接BSP自查