Merge upstream glitch

[polyamAdmin]

Conflicts:

• tsconfig.json Upstream removed entry close to an additional one for polyam-glitch. Removed as upstream.
• app/models/custom_filter.rb Upstream added new constant close to one added for polyam-glitch. Added constant.
• app/models/invite.rb Upstream made changes close to a polyam-glitch change. Applied code change.
• app/models/user_invite_request.rb Same as above.
• app/services/notify_service.rb Upstream added a new type close to one added for polyam-glitch. Added type.
• config/locales/simple_form.en-GB.yml Upstream removed lines close to ones modified to say "toot". Deleted lines and kept "toot".
• config/locales/simple_form.en.yml Upstream changed string modified to say "toot". Applied changes and kept "toot".

Also includes following changes:

• Updated app/javascript/flavours/polyam/theme.yml
• Moved and updated everything in app/javascript/flavours/polyam/packs

Ported changes:

• 74012831f61a36b7f52540c5ccafa0f9692a6596 (Refactor and SCSS only)
• 0ec061aa8f7383330b26b3323d2fafd9ec7663e3
• 4ef0b48b951d65920d3a3d9cdfd099967c5e4f6d
• de4a7bf53159f72a9a122bf8df21e8d5f4ad7512
• 65093c619fdd1b18a4cf0c288051d8c524d5f434
• 4f4b77920eeb3ba65346862d489945494dfeab64
• 36909065b544d06e8487f1e0679e595fd01a7f22
• 4527e012daa61dc07258eaedf3e03179b59fca8d
• b9b4db483cc588a2eb334b63fe6740c8dad9b57b
• 7d3fe2b4c3cd9511df8f8026890c71b2119719f3
• 26e10aa203d18e452cdf836209875f05a6e01882
• 616e2f26668d578ae81043a3836e881178d3e806
• 9e260014c72fa83740d70d2d603e836f86e64b55

Additional changes:

• 81eb6021fb3ef37fa47a4500d2f2c6d2ab2e4a39 (Follow-up to #532)