feat(lsp): add vala language support

[ttys3]

fix #2224

one question: Vala allows comments to be recorded in code in different ways. but in languages.toml we can only config a single comment-token = "//", how can we to block comment toggle action ?

// Comment continues until end of line

/* Comment lasts between delimiters */

/**
 * Documentation comment
 */

refs:

lang server: https://github.com/vala-lang/vala-language-server

ts: https://github.com/vala-lang/tree-sitter-vala

https://wiki.gnome.org/Projects/Vala/StringSample

https://learnxinyminutes.com/docs/vala/

https://naaando.gitbooks.io/the-vala-tutorial/content/en/3-basics/comments.html

---

demo vala code to test:

// Single line comment

/* Multiline
Comment */

/**
* Documentation comment
*/

char character = 'a';
unichar unicode_character = 'u'; // 32-bit unicode character

int i = 2; // ints can also have guaranteed sizes (e.g. int64, uint64)
uint j = -6; // Won't compile; unsigned ints can only be positive

class HelloWorld: Object {
    private uint year = 0;

    public HelloWorld () {
    }

    public HelloWorld.with_year (int year) {
        if (year>0)
            this.year = year;
    }

    public void greeting () {
        if (year == 0)
            print ("Hello World\n");
        else
            /* Strings prefixed with '@' are string templates. */
            print (@"Hello World, $(this.year)\n");
    }
}

void main (string[] args) {
    var helloworld = new HelloWorld.with_year (2022);
    helloworld.greeting ();
}

[the-mikedavis]

Some scopes in highlights.scm need to be adjusted to match the list here: https://github.com/helix-editor/helix/blob/6047506ec56787e5a87d0dfe9cb90646004becf5/book/src/themes.md#scopes

For example, @float becomes @constant.numeric.float, @property and @field become @variable.other.member, @parameter becomes @variable.parameter, etc.

[ttys3]

@variable.parameter

updated, PTAL

[ttys3]

chore: adjust vala boolean, character, regex

PTAL

[the-mikedavis]

in languages.toml we can only config a single comment-token = "//", how can we to block comment toggle action?

Toggling block comments is not currently supported (see #1505 and #1937 (comment)). For now, just the line comment will do 👍

[the-mikedavis]

I think these suggested edits make the variable highlights look better, in particular the

(identifier) @variable

highlights variables as they are used (rather than assigned). It's not always different than them being not highlighted depending on the theme - some themes highlight variables the same as the foreground theme.

Also I think it would make sense to replace the @include scope with @namespace based on how it's used.

I haven't used vala before though so I might be wrong about these

[ttys3]

rebased and applied suggested changes.

[the-mikedavis]

Thanks!