fix types default export (#5852)

[Muhammad-Altabba]

Description

A replacement of the MR #5852. Original description:

Some packages export their classes as default, but .d.ts definitions don't have default export. So it is fixed it by adding export default to .d.ts files
This PR only fixes .d.ts and types tests, so it doesn't affect actual code and can't break anything

Fixes #5543

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist for 1.x:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• I ran npm run build with success.
• I have tested the built dist/web3.min.js in a browser.
• I have tested my code on the live network.
• I have checked the Deploy Preview and it looks correct.
• I have updated the CHANGELOG.md file in the root folder.

Please, check #5543 (comment) for more insights.

[coveralls]

Pull Request Test Coverage Report for Build 4256416483

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 75.018%

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Totals
Change from base Build 4254337306:	0.0%
Covered Lines:	3310
Relevant Lines:	4161

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💛 - Coveralls