[mui-system][style] bug fix for style value check color in nullable object

[DarhkVoyd]

Description
In PR #39071, we added checks to getStyleValue to throw a warning in development mode to double check if the prop value resolved from themeMapping was intentionally object. This was to ensure that setting object values to css such as color does not fail silently. But, the warning was also thrown on setting object values when necessary such as typography to body1 which quickly led to spam a lot of warnings.

Changes Made:

• Added a function to check if a given string is a colour in any of the standard color styles (hex, rgb, rgba, var, scss).
• Updated the getStyleValue function to check if the resolved value is non-null object and only throw warning if the object immediately contains color values.
• Updated all tests from the previous PR to better fit the new getStyleValue.

Testing:

I have updated all relevant tests from the original PR, style.test.js, palette.test.js, styleFunctionsSx.test.js and Typography.test.js file to ensure that the changes work as expected. The tests include checking that the warning is only thrown on objects which immediately contain colours.

• I have followed (at least) the PR section of the contributing guide.

Closes #39399

[mui-bot]

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[DiegoAndai]

Should we reopen #38478?

[DarhkVoyd]

@DiegoAndai I do think we need to reopen but as of now I haven't been able to find a better way to solve it.