Switch to compose state and kotlin flows - 3. iteration (#307)

* Removed deprecated live data methods

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

* Removed deprecated live data methods

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

* Replaced LiveData usages with Flow

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

* Added `stateIn`

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

* Added null check

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

* Moved share logic

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

* Removed messages

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

* Added Compose ViewModel dependency

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

* Added ViewModel for the base theme

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

* Moved dark theme flow to model

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

* SWitched `Eagerly` by `WhileSubscribed`

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

* Remove redundant initializers

* Initialize flows close to their declaration

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