Split out reports dependencies

[tsalo]

Related to #934 and #976. To be honest, this doesn't quite close either, but it might be a useful first step. I'm fine going the monorepo route, but since I have no experience with that approach I decided to take a first step that just splits out the reports-specific dependencies into a new dependency group.

Changes proposed in this pull request:

• Move bokeh and jinja2 into a new dependency group (reports).
• Move bokeh and jinja2 imports into the relevant functions, so we don't get import errors unless we use those functions.
• Add a function that checks for the existence of these imports when no-reports isn't enabled.

[codecov]

Codecov Report

Attention: Patch coverage is 90.62500% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 89.77%. Comparing base (af5e99a) to head (f8f9cb5).

Files	Patch %	Lines
tedana/utils.py	90.00%	2 Missing ⚠️
tedana/workflows/tedana.py	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #977      +/-   ##
==========================================
- Coverage   89.80%   89.77%   -0.03%     
==========================================
  Files          26       26              
  Lines        3540     3559      +19     
  Branches      621      623       +2     
==========================================
+ Hits         3179     3195      +16     
- Misses        212      214       +2     
- Partials      149      150       +1     

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[eurunuela]

The PR is now up to date with main. We now have to decide whether we take this route or go the monorepo route.