Implement --exact-match Flag for bundle info / show / open

[OughtPuts]

What was the end-user or developer problem that led to this PR?

bundle info, bundle show, and bundle open currently fall back to regex matching when the provided gem name is not an exact match. That can produce surprising results for short or partial names. For example, a command like bundle info rack can end up matching another gem such as crack, or prompt with multiple fuzzy matches when the user intended to target a single exact gem name.

This PR addresses: #9441

This PR adds a way for users to opt out of that fuzzy behavior when they want strict lookup semantics.

What is your fix for the problem, implemented in this PR?

This PR adds a new --exact-match flag to bundle info, bundle show, and bundle open.

When the flag is provided, these commands skip the existing regex fallback and only resolve a gem when its name exactly matches the user input. When the flag is not provided, the existing behavior is preserved, including fuzzy matching and interactive disambiguation when multiple gems match.

Implementation details:

• Added --exact-match as a Thor option for all three commands.
• Kept Bundler::CLI::Common.select_spec unchanged to keep the change light-touch.
• Added a small shared helper in Bundler::CLI::Common that decides whether to call select_spec with regex matching enabled or disabled based on the new flag.
• Updated the command manpages for bundle info, bundle show, and bundle open.

Tests were added to cover both behaviors for all three commands:

• --exact-match returns the exact spec without prompting
• omitting the flag keeps the existing fuzzy-match behavior

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags