This is a low-level helper for the template matching code; probably don't use it directly.

Given a template, parse it and return:

• a list of variable names
• a glob for searching Earthstar using queryByGlob()
• a regular expression with named capture groups which can extract the values of the variables from a path.

A variable in the template is any alphanumeric chars or underscores, in curly braces like {example} or {EXAMPLE} or {example_1}, starting with a non-number.

Templates can also contain * and ** according to the glob rules. Those wildcards are not counted as variables but are allowed to expand during the regex phase.

Rules for templates:

• Variable names must only contain upper and lower letters, numbers, and underscore.
• They cannot start with a number.
• They cannot be empty {}.
• Two variables cannot be directly touching {like}{this}.
• A variable cannot be directly touching a star {likeThis}* or *{likeThis}.

If variable names don't match these rules, a ValidationError will be thrown.