Fix binding of explicitly numbered parameters

[mvduin]

Parameters of the form ?1, ?2, etc aren't named parameters, you're explicitly specifying the parameter index, allowing indexed (i.e. unnamed) parameters to be explicitly ordered, reused, or skipped. Somewhat oddly however sqlite still reports their name* from sqlite3_bind_parameter_name, causing better-sqlite3 to force it to be passed by name which is not what's expected or desired.

(* or rather their first name, e.g. SELECT ?01, ?1, ?001 has a single parameter whose reported name is ?01 though I don't think sqlite documents which of the three names is returned in this case.)

This patch-set fixes this and adds some tests for explicitly numbered parameters (there were none whatsoever).

The reason I care about explicitly numbered parameters is because I'm using tagged templates for queries, and using explicit numbering allows this to be much more robust against e.g. parts of the query being comments out. Here's a highly simplified minimalistic demo of this concept:

class Database extends require('better-sqlite3') {
	#compiled = new WeakMap;
	compile( tmpl ) {
		let stmt = this.#compiled.get( tmpl );
		if( stmt )
			return stmt;
		let sql = '';
		tmpl.forEach( (chunk, i) => {
			if (i) sql += ` ?${i} `;
			sql += chunk;
		});
		console.log(`COMPILING: \x1b[2m${sql.trim()}\x1b[m`);
		stmt = this.prepare( sql );
		this.#compiled.set( tmpl, stmt );
		return stmt;
	}
	get( tmpl, ...args ) {  return this.compile( tmpl ).get( ...args );  }
}

let db = new Database(':memory:');
function demo( a, b ) {
	return db.get`SELECT ${a} as a, ${b} as b`;
}
console.log( demo( 1, 2 ) );
console.log( demo( 'foo', 'bar' ) );

function demo2( a, b, c ) {
	return db.get`
		SELECT ${a} as a,
		--	${b} as b,  -- FIXME can we get rid of this?
			${c} as c`;
}
console.log( demo2( 1, 2, 3 ) );
console.log( demo2( 'foo', 'bar', 'baz' ) );

output:

COMPILING: SELECT  ?1  as a,  ?2  as b
{ a: 1, b: 2 }
{ a: 'foo', b: 'bar' }
COMPILING: SELECT  ?1  as a,
                --       ?2  as b,  -- FIXME can we get rid of this?
                         ?3  as c
{ a: 1, c: 3 }
{ a: 'foo', c: 'baz' }

[s5bug]

What's preventing this from being merged? I'm working on improving parameter handling in a library I use that depends on better-sqlite3, and this bug has unfortunately become a blocker.