[Bug]: Runtime error for Unicode escape values in regex

[SasinduDilshara]

Description

Following Code

import ballerina/io;

public function main() {
    string:RegExp r = re `\u{1F600}`;
    io:println(r.replaceAll("😀 Hello, 🌍! ❤️", ""));
}

Gives

error: {ballerina}RegularExpressionParsingError {"message":"invalid regexp pattern: Illegal Unicode escape sequence near index 2
\u{1F600}
  ^"}
        at ballerina.lang.regexp.0:findAllGroupsImpl(regexp.bal:190)
           ballerina.lang.regexp.0:findAllGroups(regexp.bal:164)
           ballerina.lang.regexp.0:replaceAll(regexp.bal:377)

This runtime error also happen in

import ballerina/io;

public function main() {
    string:RegExp r = re `[\u{1F600}-\u{1F6FF}]`;
    io:println(r.replaceAll("😀 Hello, 🌍! ❤️", ""));
}

Steps to Reproduce

No response

Affected Version(s)

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OS, DB, other environment details and versions

No response

Related area

-> Runtime

Related issue(s) (optional)

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Suggested label(s) (optional)

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Suggested assignee(s) (optional)

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[github-actions]

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      - Reason/EngineeringMistake - The issue occurred due to a mistake made in the past.
      - Reason/Regression - The issue has introduced a regression.
      - Reason/MultipleComponentInteraction - Issue occured due to interactions in multiple components.
      - Reason/Complex - Issue occurred due to complex scenario.
      - Reason/Invalid - Issue is invalid.
      - Reason/Other - None of the above cases.