Completion item sorting order in from caluse context is not accurate

[malinthar]

Description:
The order of completion items in the from clause context can be improved to sort the iterable expressions to the
top. The order is currently as follows.

Steps to reproduce:

function getMedalStats() returns stream<MedalStatsRecord, error?> | error {
    int abc;
    string cd;
    int[] myArr;
    stream<string[], io:Error?>|error tsvStream = readTsvAsStream("/data/Medals.tsv");
    if readTsvAsStreamResult is stream<string[], io:Error?> {
        return stream from var entry in 
    } 
}

[malinthar]

Sub task of #33628