feat: Added support for adding providers through mach config directly without needing plugins

[demeyerthom]

This pull request introduces significant enhancements to the Terraform configuration generation process, focusing on enabling direct provider configurations, improving modularity, and adding support for provider requirements. The changes include adding new features, refactoring existing functionality, and updating templates to accommodate the new capabilities.

Enhancements to Terraform Provider Configuration:

• .changes/unreleased/Added-20250627-152055.yaml: Added support for defining providers directly in the Mach configuration without requiring plugins.
• internal/config/provider.go: Introduced ProviderConfigs and ProviderConfig types to manage provider configurations, including methods to retrieve provider names.
• internal/config/global.go: Added ProviderConfigs to TerraformConfig and implemented logic to warn about duplicate provider names between plugins and provider configurations. [1] [2]
• internal/config/schemas/schema-1.yaml: Updated the schema to include provider_configs and defined the structure for ProviderConfig. [1] [2]

Support for Provider Requirements:

• internal/generator/requirements.go: Added functionality to render provider requirements using a new template.
• internal/generator/templates/requirement.tmpl: Created a template for rendering provider requirements.
• internal/generator/site.go: Integrated provider requirements rendering into site-level Terraform configurations and resources. [1] [2]

Updates to Terraform Component Tags and Variables:

• internal/generator/component.go: Added ComponentTags to componentContext and updated rendering logic to include tags and additional variables in Terraform configurations. [1] [2]
• internal/generator/templates/site_component.tmpl: Updated templates to support rendering tags directly in the module configuration.

Provider Rendering Enhancements:

• internal/generator/providers.go: Added functionality to render provider configurations using a new template.
• internal/generator/templates/provider.tmpl: Created a template for rendering provider configurations.

Dependency Updates:

• go.mod: Added the github.com/flosch/pongo2/v5 dependency to support template rendering.