39 Allow for custom tooltip targetElement

[joao-m-santos]

Closes to #39

📝 Description

Added support for targetElement option inside tooltipOptions

• If undefined, it will generate tooltip anchors and attach to them (default);
• If "self", it will attach to the <svg> container element;
• If provided with an Element, it will attach to it.

💥 Is this a breaking change (Yes/No):

• No
• Yes (please describe the impact and migration path for existing Lume users)

📝 Additional Information

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.