Refined issue templates

[pasabanov]

Types of changes

• Configuration (GitHub issue templates)

Description

Changes to .github/ISSUE_TEMPLATE/bug_report.md:

1. Removed empty variables and the empty line in the front matter.
2. Changed the header style.
3. Removed redundant headers.
4. Deleted unnecessary comments.
5. Simplified the content of the Release header.

Changes to .github/ISSUE_TEMPLATE/feature_request.md:

1. Removed empty variables and the empty line in the front matter.
2. Changed the header style.
3. Deleted old headers and replaced them with new ones: Problem or Motivation and Solution or Suggestion.
4. Removed unnecessary comments.
5. Added the header Current release for easier tracking of implemented features with version association.