Add support for Azure Bicep DSL syntax highlighting with full coverage
of Bicep language features including:

- Core keywords: param, var, resource, module, output, for, in, if, etc.
- Data types: string, int, bool, object, array
- Decorators: @description, @Allowed, @minlength, @maxlength, etc.
- String interpolation with  syntax
- Comments (single-line // and multi-line /* */)
- Resource type references with @ symbol
- Operators and punctuation

Supports file extensions: .bicep, .bicepparam
MIME type: text/x-bicep

Includes comprehensive test file demonstrating all major features.

Fixes: pygments#2938