Use implicit namespace plugins for import and export (#1216)

* behavior outline
* FIrst pass at allow external plugins
* remove template exporter
* Add listing of active plugins to '--version' output
* Documentation for plugins
* [Docs] add custom imports and exporters to site TOC
* [Docs] better linewrapping
* enforce positive initial linewrap
  Check column widths
  update gitignore
  throw error when linewrap too small
  simply check for large enough linewrap value
* delete unused error message
* PR feedback
  make exception more informative
  update check_linewrap signature in src and test
  make check_linewrap a free function
* delete unused function
* delete else..pass block
* newline for make format
* Include dates_exporter
* Use Base classes for importer and exporters.
* [Docs] improve documentation of custom Importers and Exporters
* [Testing] separate run with external plugin!
* basic behavior test
* prototype unittest for JSON Exporter
  test for unimplemented method
* make format
  delete unused imports
* Remove 'importer' or 'exporter' from filenames where not needed
* [Test] run different tests with or without the external plugins installed
* [Test] move test rot13 plugin into git tree
  from 0dc912af82
* consolidate demo plugins to common package
* [Docs] name page for plugins
* [Docs] include the sample plug in code files directly
* style fixes
* [test] determine whether to run external plug in tests based on installed packages
* improved code documentation
* style fixes for GitHub actions
* Convert "short" and "pretty" (and "default") formaters to plugins
  further to https://github.com/jrnl-org/jrnl/pull/1177
* more code clean up
  tests pass locally...now for GitHub...
* [tests] dynamically determine jrnl version for plugin tests
* [GitHub Actions] direct install of testing plugins
* Remove template code
* [plugins] meta --> collector
* [Docs] create scripted entries using an custom importer
* (closer to) being able to run behave tests outside project root directory
* We already know when exporter to use
  Don't re-calculate it!
* [Tests] don't name test plugin 'testing"
  If so named, pip won't install it.
* [Test] run behave tests with test plugins outside project root
* [Test] behave tests pass locally
* [Docs] fix typo
* [GitHub Actions] run test commands from poetry's shell
* black-ify code
* [GitHub Actions] move downstream (rather than up) to run tests
* [GitHub Actions] set shell to poetry
* [GitHub Workflows] Manually activate virtual environment
* [GitHub Actions] Skip Windows & Python 3.8
  Can't seem to find Python exe?
* [GiotHub Actions] explicitly use virtual env
* [GitHub Actions] create virutal env directly
* [GitHub Actions] better activate of Windows virtual env
* [GitHub Actions] create virtual env on Mac
* [Github Actions] install wheel and upgrade pip
* [GitHub Actions] skip virtual environments altogether
* [GitHub Actions] change directory for behave test
* Remove Windows exclusions from CI as per note -- they should be working now

Co-authored-by: Suhas <sugas182@gmail.com>
Co-authored-by: Micah Jerome Ellison <micah.jerome.ellison@gmail.com>

features/format.feature

@@ -26,6 +26,7 @@ Feature: Custom formats
         |   basic_folder    |
         |   basic_dayone    |
 
+    @skip_no_external_plugins
     Scenario Outline: JSON format
         Given we use the config "<config>.yaml"
         And we use the password "test" if prompted
@@ -48,6 +49,7 @@ Feature: Custom formats
         | basic_folder    |
         | basic_dayone    |
 
+    @skip_no_external_plugins
     Scenario: Exporting dayone to json
         Given we use the config "dayone.yaml"
         When we run "jrnl --export json"
@@ -91,6 +93,7 @@ Feature: Custom formats
         | basic_folder    |
         | basic_dayone    |
 
+    @skip_no_external_plugins
     Scenario Outline: Exporting using filters should only export parts of the journal
         Given we use the config "<config>.yaml"
         And we use the password "test" if prompted
@@ -112,6 +115,7 @@ Feature: Custom formats
         | basic_folder    |
         | basic_dayone    |
 
+    @skip  # template exporters have been removed
     Scenario Outline: Exporting using custom templates
         Given we use the config "<config>.yaml"
         And we load template "sample.template"