feat: add support for as const assertions, string literal union types, and quoted object keys

[swernerx]

This PR adds three improvements to the no-unlocalized-strings rule:

1. Automatically ignores string literals that are part of as const assertions since these are typically used to declare fixed values/constants and are not meant for translation.

Example:

// This will no longer be flagged
const ROUTES = {
  home: "/home" as const,
  settings: "/settings" as const
} 

2. When useTsTypes: true is enabled, ignores string literals that are part of string literal union types, as these usually represent predefined values rather than user-facing strings.

Example:

type ButtonVariant = "primary" | "secondary";
function Button(props: { variant: ButtonVariant }) { }

// This will no longer be flagged
Button({ variant: "primary" });

3. Added support for quoted object keys since these typically represent technical identifiers (CSS selectors, API paths, etc.) rather than user-facing strings.

Example:

// This will no longer be flagged
const styles = { 
  ":hover": { color: theme.brand },
  "[data-selected]": { background: theme.selected }
}

Testing

Added test cases for all new functionality:

• as const assertions
• String literal union types with useTsTypes: true
• Quoted object keys

All existing tests continue to pass.

[codecov]

Codecov Report

Attention: Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.70%. Comparing base (56eb2ee) to head (5c97770).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/rules/no-unlocalized-strings.ts	97.82%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #96      +/-   ##
==========================================
+ Coverage   97.45%   97.70%   +0.24%     
==========================================
  Files          10       10              
  Lines         433      479      +46     
  Branches      129      143      +14     
==========================================
+ Hits          422      468      +46     
  Misses         11       11              

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