Optimise RouteValues

[stevejgordon]

Adds a reusable ResolvedRouteValues instance for all requests where there are no RouteValues.

This reduces allocs and improves perf slightly.

|           Method |      Mean |    Error |    StdDev |    Median |  Gen 0 | Gen 1 | Gen 2 | Allocated |
|----------------- |----------:|---------:|----------:|----------:|-------:|------:|------:|----------:|
|              Old | 222.59 ns | 9.174 ns | 26.616 ns | 212.48 ns | 0.0496 |     - |     - |     208 B |
| OldParameterless |  88.45 ns | 1.761 ns |  2.582 ns |  88.09 ns | 0.0172 |     - |     - |      72 B |
|              New | 202.92 ns | 5.285 ns |  9.117 ns | 201.08 ns | 0.0496 |     - |     - |     208 B |
| NewParameterless |  11.94 ns | 0.273 ns |  0.570 ns |  11.79 ns |      - |     - |     - |         - |

Gets rid of the Resolved ResolvedRouteValues on RouteValues in favour of a lighter bool which still supports the IndexRequest requirement.

[Mpdreamz]

LGTM 👍

[github-actions]

The backport to master failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-master master
# Navigate to the new working tree
cd .worktrees/backport-master
# Create a new branch
git switch --create backport-5293-to-master
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick ---mainline 1 46caff6d1b5a7cdecb39a962df0fcfdfbd132a41
# Push it to GitHub
git push --set-upstream origin backport-5293-to-master
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-master

Then, create a pull request where the base branch is master and the compare/head branch is backport-5293-to-master.