feat: export types

[colinyip]

Description

export types in the main module so that it can be used publicly. related to #77

• Tests for the changes have been added (for bug fixes / features)
• The commit message(s) follow conventional commits
• Documentation has been added / updated (for bug fixes / features)
• Changes follow the contributing document.

Motivation and Context

Does this PR introduce a breaking change?

• Yes
• No

Which merge strategy will you use?

• Squash
• Rebase (REVIEW COMMITS)

[github-actions]

Total Coverage: 87.70%

Coverage Report

File	Branches	Funcs	Lines	Uncovered Lines
src
BbsBlsSignature2020.ts	58.49%	100%	87.50%	103, 112, 120, 125, 130, 134, 208, 209, 220, 221, 319, 320, 323, 324, 342, 343, 347, 348, 362, 363, 386, 47, 48, 51, 63, 68, 72, 75, 79, 80, 81, 81, 81, 82
BbsBlsSignatureProof2020.ts	62.96%	81.25%	85.15%	166, 167, 176, 294, 295, 300, 336, 338, 342, 348, 379, 384, 396, 397, 399, 400, 418, 419, 423, 424, 43, 68, 69, 82, 91
deriveProof.ts	50%	100%	85.71%	33, 34, 52, 81, 82
index.ts	100%	100%	100%
utilities.ts	70%	100%	96.67%	119, 43, 79, 80