This commit adds the feature to select a date in the future
in order to see future allocations, would it be for accrual plans
granting new allocated days, lost days due to expired allocations
or allocations that are not yet available to the employee.
The date selector only appear when the employee has accrual allocation,
in which case the feature is more relevant.
This feature comes with a major refactoring of hr_holidays
methods to handle some edge cases in the management of leaves.
The refactoring also includes the removal of the 'draft' and 'cancel'
state in allocations.
This commit also removes unused imports and implements some linting fixes.
task-2675380
closesodoo/odoo#108148
Related: odoo/upgrade#4238
Related: odoo/enterprise#35157
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>