new build on save with watch mode

[Techatrix]

This PR replaces the current build on save implementation with a new one that is based on Zig's zig build --watch feature. This can be combined with the build_on_save_args config option to enable incremental compilation. fixes #2001

Here is a small showcase where I use the equivalent of zig build check --watch -fincremental:

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I used the Error Lens extension to display the error messages inline.

The minimum runtime Zig version has been bumped from 0.12.0 to 0.14.0-dev.310+9d38e82b5. This means that the latest mach nominated zig version (0.14.0-dev.1911+3bf89f55c) is still supported.
The build on save diagnostics are no longer removed after editing the document. The source location of the error message is not being updated when the document gets modified but this can be implement in the future.

• fixes Diagnostics relatedInformation contain invalid URLs #2095
• partially addresses Check diagnostics not highlighting full type issue #2060
• errors are stored as std.zig.ErrorBundle which unblocks use reference trace to provide better build-on-save source locations for errors #2018

I have only tested this on Linux and Windows with VS Code. Who know what kind of bugs are still lurking around 🤷

[leecannon]

I've tried this with a few of my projects and it works well ⚡

[lishaduck]

@Techatrix, is there a way to turn this off? I skimmed the diff and I didn't see one.
This breaks build_on_save in VS Code on macOS (#2221/ziglang/zig#21905)

[kristoff-it]

On macOS there are two bugs related to this feature, one is the one linked above, the second is that --watch crashes on macOS (fixed here, should become available in 0.14.1) and when that happens in ZLS, you just see ZLS stop working.

[Techatrix]

@Techatrix, is there a way to turn this off? I skimmed the diff and I didn't see one.

No, this PR has replaced the previous build on save implementation. Excluding bugs like these, there should be no reason to need the old implementation.

If no progress is being made on ziglang/zig#21905, I will look into patching ZLS.