The data mapper generates an invalid function for types starting with a digit

[nipunayf]

Description:
$title. The OpenAPI more often generates records that start with digits, and hence it is common to have such records.

Screen.Recording.2024-04-30.at.3.35.05.PM.mov

Steps to reproduce:
Create a transformation function using the data mapper for the following types.

type '1Record record {|
    string id;
|};

type '2Record record {|
    string id;
    string name;
|};

Affected Versions:
Ballerina 2201.8.6 (Swan Lake Update 8)

OS, DB, other environment details and versions:
OS: macOS 14.4.1 23E224
JDK: openjdk 20.0.2 2023-07-18

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