This makes copying such types much cheaper and will allow us to
intern common struct types in the future too. This further
drops the sample cost for langtype.rs from ~6.6% down to 4.0%.
We are now also able to share/intern common struct types.
Before:
```
Time (mean ± σ): 1.073 s ± 0.021 s [User: 0.759 s, System: 0.215 s]
Range (min … max): 1.034 s … 1.105 s 10 runs
allocations: 3074261
```
After:
```
Time (mean ± σ): 1.034 s ± 0.026 s [User: 0.733 s, System: 0.201 s]
Range (min … max): 1.000 s … 1.078 s 10 runs
allocations: 2917476
```
This allows us to cheaply copy the langtype::Type values which
contain such a type. The runtime impact is small and barely noticable
but a sampling profiler shows a clear reduction in samples pointing
at langtype.rs, roughly reducing that from ~8.6% inclusive cost
down to 6.6% inclusive cost.
Furthermore, this allows us to share/intern common types.
Before:
```
Benchmark 1: ./target/release/slint-viewer ../slint-perf/app.slint
Time (mean ± σ): 1.089 s ± 0.026 s [User: 0.771 s, System: 0.216 s]
Range (min … max): 1.046 s … 1.130 s 10 runs
allocations: 3152149
```
After:
```
Time (mean ± σ): 1.073 s ± 0.021 s [User: 0.759 s, System: 0.215 s]
Range (min … max): 1.034 s … 1.105 s 10 runs
allocations: 3074261
```
This removes a lot of allocations and speeds up the compiler step
a bit. Sadly, this patch is very invasive as it touches a lot of
files. That said, each individual hunk is pretty trivial.
For a non-trivial real-world example, the impact is significant,
we get rid of ~29% of all allocations and improve the runtime by
about 4.8% (measured until the viewer loop would start).
Before:
```
Benchmark 1: ./target/release/slint-viewer ../slint-perf/app.slint
Time (mean ± σ): 664.2 ms ± 6.7 ms [User: 589.2 ms, System: 74.0 ms]
Range (min … max): 659.0 ms … 682.4 ms 10 runs
allocations: 4886888
temporary allocations: 857508
```
After:
```
Benchmark 1: ./target/release/slint-viewer ../slint-perf/app.slint
Time (mean ± σ): 639.5 ms ± 17.8 ms [User: 556.9 ms, System: 76.2 ms]
Range (min … max): 621.4 ms … 666.5 ms 10 runs
allocations: 3544318
temporary allocations: 495685
```
We're compatible across minor versions, only the major version change
would mean incompatibility. This way for example find_package(Slint 1.6.0)
will work with newer versions and makes it a minimum version specifier.
Replaces the use of NPM with PNPM. This should make it quick and easy to update any of the dependencies as dependabot will now see everything in one go.
The length is an important property of a string and should be available
as a getter. The new size() method is consistent with std::string.
ChangeLog: [C++] Added `SharedString::size()`
As a drive-by, this introduces a macro that allows for explicit logging to console.error (which goes to stderr). This is something we should gradually start using, as it allows for capturing on the Node.js side (by the user or our tests).
