[TypeScript][Samples/Templates] Update TypeScript ESLint version

[Batta32]

Purpose

What is the context of this pull request? Why is it being done?
This pull request fixes the following warning of the TypeScript ESLint library

WARNING: You are currently running a version of TypeScript which is not officially supported by typescript-estree.

You may find that it works just fine, or you may not.

SUPPORTED TYPESCRIPT VERSIONS: >=3.2.1 <3.6.0
YOUR TYPESCRIPT VERSION: 3.6.2

Changes

Are there any changes that need to be called out as significant or particularly difficult to grasp? (Include illustrative screenshots for context if applicable.)

• Update ESLint version from ^1.10.2 to ^2.1.0.
• Fix several type casting.
• Disable TSLint rule prefer-type-cast.

Tests

Is this covered by existing tests or new ones? If no, why not?
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Testing Steps

1. Open the generator folder and run npm install to install dependencies.
2. Open a terminal and execute npm link to link the package of the project locally.
3. From a terminal in different folder execute yo botbuilder-assistant or yo botbuilder-assistant:skill.
4. The output of the generator should not show the message warning specified in the Purpose section.

Feature Plan

Are there any remaining steps or dependencies before this issue can be fully resolved? If so, describe and link to any relevant pull requests or issues.
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Checklist

General

• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the appropriate tests
• I have updated related documentation

Bots

• I have validated that new and updated responses use appropriate Speak and InputHint properties to ensure a high-quality speech-first experience
• I have replicated language model changes across the English, French, Italian, German, Spanish, and Chinese .lu files and validated that deployment is successful

Deployment Scripts

• I have replicated my changes in the Virtual Assistant Template and Sample projects
• I have replicated my changes in the Skill Template and Sample projects