* Make throwOnError=true the new default
* Handle JS errors as part of the RPC request/response flow
* Return a new Result type with .Err on it
This enables constructs on the form:
```handlebars
{{ with transform.ToMath "c = \\foo{a^2 + b^2}" }}
{{ with .Err }}
{{ warnf "error: %s" . }}
{{ else }}
{{ . }}
{{ end }}
{{ end }}
```
Note that the new `Result` type behaves like `template.HTML` (or a string if needed) when printed, but it will panic if in a error state.
Closes#12748
The template packages are based on go1.20.5 with the patch in befec5ddbbfbd81ec84e74e15a38044d67f8785b added.
This also includes a security fix that now disallows Go template actions in JS literals (inside backticks).
This will throw an error saying "... appears in a JS template literal".
If you're really sure this isn't a security risk in your case, you can revert to the old behaviour:
```toml
[security]
[security.gotemplates]
allowActionJSTmpl = true
```
See https://github.com/golang/go/issues/59234Fixes#11112
This commit replaces the main part of `helpers.StripHTML` with Go's implementation in its html/template package.
It's a little slower, but correctness is more important:
```bash
BenchmarkStripHTMLOld-10 680316 1764 ns/op 728 B/op 4 allocs/op
BenchmarkStripHTMLNew-10 384520 3099 ns/op 2089 B/op 10 allocs/op
```
Fixes#9199Fixes#9909Closes#9410
