source-http-ingest: support path parameters

[psFried]

Description:

Introduces support for capturing path parameters from incoming requests. The paths in the endpoint config are now allowed to specify parameters using the OpenAPI syntax. For example, the path
/vendors/{vendorId}/products/{productId} can now be used to extract the vendorId and productId, which will be added to a /_meta/pathParams JSON object. The OpenAPI syntax was chosen because it's well-known and documented, and because it's simple and limited. This makes it easy to parse and less likely to result in surprising behavior. The syntax is documented at: https://swagger.io/docs/specification/v3_0/paths-and-operations/#path-templating

The /_meta/reqPath property was also added in order to record the configured path at which the request was handled.

Any path parameters are added as required properties in the discovered collection writeSchema. This allows them to be used as collection keys just by editing the collection in the UI during capture creation.

Workflow steps:

• Enter a path in the endpoint config like /{paramA}/{paramB}
• Send a request to /foo/bar
• The captured document will include:

{
  "_meta": {
    "pathParams": {"paramA": "foo", "paramB": "bar"}, 
    "reqPath": "/{paramA}/{paramB}"
  }
}

Documentation links affected:

I'll put up a separate PR to update: https://docs.estuary.dev/reference/Connectors/capture-connectors/http-ingest/

Notes for reviewers:

This feature was suggested by a user in Slack, who would otherwise need to configure many different endpoint paths.

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This change is 

[williamhbaker]

LGTM