Add automatic CSharpier formatting

Replace CSFlex tool with source generator

Replace PxCoco tool with source generator

Closes PRX-67

Bumps [Microsoft.Build.Framework](https://github.com/dotnet/msbuild) from 17.4.0 to 17.5.0.
- [Release notes](https://github.com/dotnet/msbuild/releases)
- [Changelog](https://github.com/dotnet/msbuild/blob/main/documentation/Changelog.md)
- [Commits](https://github.com/dotnet/msbuild/commits)

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Bumps [Microsoft.Build.Utilities.Core](https://github.com/dotnet/msbuild) from 17.1.0 to 17.4.0.
- [Release notes](https://github.com/dotnet/msbuild/releases)
- [Changelog](https://github.com/dotnet/msbuild/blob/main/documentation/Changelog.md)
- [Commits](https://github.com/dotnet/msbuild/commits)

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Bumps [Microsoft.Build.Framework](https://github.com/dotnet/msbuild) from 17.1.0 to 17.4.0.
- [Release notes](https://github.com/dotnet/msbuild/releases)
- [Changelog](https://github.com/dotnet/msbuild/blob/main/documentation/Changelog.md)
- [Commits](https://github.com/dotnet/msbuild/commits)

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Breaking: remove PCommand.IsPure, PCommand.Groups, PCommand.IsInGroup, PCommand.AddToGroup, PCommand.RemoveFromGroup (groups are now tracked in the command table)

Breaking: `sys.rt.compile_to_cil` will now compile the entire compound (not just the current application)

Fix bug in stack context passing across module boundaries.

Fix broken prx scripts

Remove stored tests (round-trip). They have been disabled for a while and there are no plans to bring back support for round-tripping.

Goes for both `require` and `add`.

The behavior is disabled by default for PXS 1, but enabled by default for PXS 2.

You can now write

```
namespace target export source(*);
```

instead of

```
namespace target { } export source(*);
```

If you omit the braces, an export clause or a semicolon are mandatory (e.g., `namespace ns` alone is not legal)

Compiler will now recover with constant `false`.

Also:
- upgrade to windows-2022

For the story to be complete, we also need to publish the single binary (on both platforms).

Enable single-file (runtime-included) prx binary (~66MB).

Also:
- implement reading of files from embedded resources for `build does add` and `build does require`.

Bumps [Microsoft.Build.Utilities.Core](https://github.com/dotnet/msbuild) from 16.11.0 to 17.1.0.
- [Release notes](https://github.com/dotnet/msbuild/releases)
- [Commits](https://github.com/dotnet/msbuild/compare/v16.11.0...v17.1.0)

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updated-dependencies:
- dependency-name: Microsoft.Build.Utilities.Core
dependency-type: direct:production
update-type: version-update:semver-major
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Bumps [Microsoft.Build.Framework](https://github.com/dotnet/msbuild) from 16.11.0 to 17.1.0.
- [Release notes](https://github.com/dotnet/msbuild/releases)
- [Commits](https://github.com/dotnet/msbuild/compare/v16.11.0...v17.1.0)

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updated-dependencies:
- dependency-name: Microsoft.Build.Framework
dependency-type: direct:production
update-type: version-update:semver-major
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The grammar excluding that scenario was a leftover from the time when the rules around GetSetComplex were more strict.

Fixes PRX-65

Fixes PRX-64.

(doesn't really matter)

Excluding generated files for now.

`namespace import x;` doesn't do anything. Either `x` is already in scope (in which case, this is a no-op) or `x` is not in scope (which results in an error symbol being declared).

For now, I've decided not to immediately emit an error for unresolved symbols. Not 100% sure if I'm going to keep imports this way.

The rationale is that Prexonite Script doesn't have robust IDE support and thus micro-managing imports is painful. Having a compilation fail because of an unused but unresolved import sounds annoying to me.

Also:
- Introduce `GetNextPosition` method. See PRX-57