Add Max Length and Text Counter Builder

[luckycreationsindia]

The code has been updated to allow setting the maximum character limit for the SearchField widget in Dart. In addition to defining the maxLength, you can also specify how to enforce the length limit and create a widget for displaying the current length/limit information.

This will add feature to allow adding maxLength and related changes (Enforcement and Counter)

This will fix this issue:

Add Max Length and Option to disable counter for TextFormField #145

Pre-launch Checklist

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] I listed at least one issue that this PR fixes in the description above.
• [x] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making, or this PR is [test-exempt].
• [x] All existing and new tests are passing using flutter test

If you need help, consider pinging the maintainer @maheshmnj

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[maheshj01]

Thank you for your contribution @luckycreationsindia