Design Proposal: #5981 Performance of Rewrite Middleware

## Summary

Design proposal for https://github.com/dotnet/aspnetcore/issues/5981. Adding benchmarks for Rewrite Middleware project in [aspnet/benchmarks](https://github.com/aspnet/Benchmarks).

## Motivation and goals

- Seeing how the increased number of Rewrite rules effects the performance.
- Gauge how these effected by changes to Rewrite middleware in general.
- Close [5981](https://github.com/dotnet/aspnetcore/issues/5981) it appears to be the oldest help-wanted labelled issue.

## In scope

Using [5981](https://github.com/dotnet/aspnetcore/issues/5981) as a starting point. Single rule, thousand rules and ten thousand rules will be added from database.

## Out of scope

None.

## Risks / unknowns

None.

## Examples

Because task is focused on benchmarking a feature rather than fixing a bug or adding a feature. Currently I can't add any examples to this section.

However I found a previous PR [2233](https://github.com/aspnet/Benchmarks/pull/2033) that have a familiar subject to [5981](https://github.com/dotnet/aspnetcore/issues/5981) . In the below draft PR, I tried to show what I kind of imagine doing if this design approval goes ahead.

**Disclaimer: I read through the contributor guidelines, that's why I opened this Design Proposal in the first place. Without getting approval from the team, there is no point to writing code. I did the PR below because, it's much easier to demonstrate a point like this. So if it's something team can use, great. If they can't, it's completely fine.**

[2209](https://github.com/aspnet/Benchmarks/pull/2209)

There are multiple things that won't be the same but done so I can just get something working.
Some of them are below.

1-Editing postgres-techempower docker file.
2-Using the same SQL script for postgres-techempower.
3-Using that docker container for the scenario.

Start by reviewing the aspnet/Benchmarks project and the referenced PR 2209, then inspect the postgres-techempower Docker file and SQL script described in the proposal. Confirm the approved benchmark design for Rewrite Middleware with single, 1,000, and 10,000 rules loaded from a database, and compare the results against the goals before considering the work complete.

Written by the indexing model from the issue text.