Fix adding new opens when namespace declaration is on 1st line

[vzarytovskii]

Fix for #12083, only happens when namespace is on the 1st line of the document, because of this (ctx.Pos.Line = 1 here):

fsharp/src/fsharp/service/ServiceParsedInputOps.fs

Lines 1665 to 1677 in 76e65ac

	| ScopeKind.Namespace ->
	// for namespaces the start line is start line of the first nested entity
	if ctx.Pos.Line > 1 then
	[0..ctx.Pos.Line - 1]
	|> List.mapi (fun i line -> i, getLineStr line)
	|> List.tryPick (fun (i, lineStr) ->
	if lineStr.StartsWithOrdinal("namespace") then Some i
	else None)
	|> function
	// move to the next line below "namespace" and convert it to F# 1-based line number
	| Some line -> line + 2
	| None -> ctx.Pos.Line
	else 1

Probably can be simplified with removing the codnition alltogether.

I've tested it on:

• namespace on 1st line
• namespace is not on 1st line
• with existing opens
• without opens
• without namespace.

[cartermp]

nice