[StaticWebAssets] Adds fingerprinting support for assets

[javiercn]

Adds support for fingerprinting assets

• Fingerprinting works by defining expressions on the RelativePath of assets.
• Expressions contain tokens like [.{fingerprint}] which allow us to define replacements that need to happen as part of the build.
• Expressions might result in more than one endpoint if they are marked as optional with either ? or !. These modifiers determine how the file is addressable in standalone scenarios.
  • ? signifies that the file will not have its name replaced to add the expression.
  • ! signifies that the file will have its name replaced to add the expression.
• Expressions can contain embedded values via {.fingerprint=value} syntax, which makes it so that value takes precedence when reducing the expression to its literal form.
• The expressions are retained through the build until the last moment when we replace them with values to produce the final path/routes. This allows us to refer to assets/endpoints logically through the build.
• Any endpoint with a replaced value on its route, gets assigned a 'label' in its properties as well as the values that were replaced on the expression used to define that endpoint.
  • The label is the endpoint path without any token expression.
  • The replaced values are the list of values that were applied to the route.
  • The combination of label + values allows the endpoint to be uniquely identified with a human-addressable name.

Scoped CSS

• Scoped CSS asset project bundles are updated to fingerprint the file and offer the non-fingerprinted endpoint with [.{fingerprint}]!.bundle.scp.css
• Scoped CSS app bundles are updated to offer a fingerprinted endpoint with [.{fingerprint}.styles.css
• ConcatenateCss is updated to rely on endpoints.
• Three new tasks help working with endpoints.
  • FilterStaticWebAssetEndpoints to filter a list of endpoints based on a configurable set of criteria.
  • UpdateStaticWebAssetEndpoints to modify a header, property, or selector of a group of endpoints. Options are RemoveAll, Remove, Append, Replace.
  • ResolveEndpointRoutes to produce the final URL that can be used on Tasks that need to consume the endpoint path

[dotnet-policy-service]

Thanks for your PR, @javiercn.
To learn about the PR process and branching schedule of this repo, please take a look at the SDK PR Guide.

[javiercn]

Closing in favor of #41244