Make "Refresh collection list" more visible (bitfireAT/davx5#266)

* Added refresh collections fab

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Added listener for clicks on refresh collections fab

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Adjusted sizing

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Updated tooltip and description for collections sync

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Removed Snackbar

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added warning for null serviceId

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Changed refresh collections service id fetching method

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Tooltip updates on refresh collections list

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Migrate to ViewPager2; show "Refresh collections" for WebCal, too

* Added refresh collections fab

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Added listener for clicks on refresh collections fab

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Adjusted sizing

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Updated tooltip and description for collections sync

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Removed Snackbar

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added warning for null serviceId

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Changed refresh collections service id fetching method

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Tooltip updates on refresh collections list

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Migrate to ViewPager2; show "Refresh collections" for WebCal, too

* Changed collections refresh action update method

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Use lambda syntax for observers

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Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>
Signed-off-by: Arnau Mora <arnyminerz@proton.me>
Co-authored-by: Ricki Hirner <hirner@bitfire.at>
Co-authored-by: Sunik Kupfer <kupfer@bitfire.at>