This is a simple renaming without adaptation.

While displaying no content help, hovering over link was not displaying cursor
as a pointer type.

This bug has been introduced with the new design on nocontent helpers.

* account, board, hr_holidays, mail, sale, website_sale

Small fixes on nocontent onboarding screens.

Initial commit: https://github.com/odoo/odoo/commit/a87d761fdbf345ada5dc93e0a686b08a0f5a0417

Details:

- list: centered;
- pivot/graph: centered + empty folder face;
- Dashboard app with nocontent helper;
- Discuss inbox/starred: centered without neutral/smiling faces;
    => no faces because it's too much with animated
       rainbow man when emptying the any of the boxes.
- hr_holidays: fixed onboarding screens;
- (technical) dropped obsolete 'o_view_nocontent_container' style;
- manual reconciliation 'nothing to reconcile': centered + inside form sheet;
    => renamed account's o_view_nocontent to o_view_noreconciliation,
       so that it doesn't use the style of views.less.
- kanban: nocontent helper above the columns (if any);
- texts "no order to upsell"/"abandonned cart" paragraph split in two.

Before this commit, it was not possible to display a help message in a
kanban view, if it is grouped.  This is an issue, from an onboarding
point of view.  Imagine a new user, creating a project.  After it
creates a few columns, it is not clear what to do.

With this commit, we display the nocontent help message in a grouped
kanban view, if the user is not currently creating a new column. This
allows the user to focus on its work, by working in phases: first, he is
prompted to create project column, then when he decides that he is done,
the user interface shows the nocontent help message, which guides
her/him to the process of creating a task.

We would like to make the "no item found" screens more appealing.

Before this commit, it shows a small help tip in the top-left
corner of the screen, just below the "Create" button.

With this commit, these help tips have been replaced by onboarding
screens, which consist of a picture and some text below, both of which
are horizontally centered.

The texts have been slightly changed, so that they are shorter and clearer.

Considered modules:

(A)
    account,
    account_asset,
    account_budget,
    account_test,
    account_voucher,
    analytic
(B)
    barcodes,
    base,
    base_automation,
    board
(C)
    calendar,
    contacts,
    crm
(D)
    delivery
(E)
    event
(F)
    fleet
(G)
    gamification,
    google_drive
(H)
    hr,
    hr_attendance,
    hr_contract,
    hr_expense,
    hr_gamification,
    hr_holidays,
    hr_payroll,
    hr_recruitment,
    hr_timesheet
(I)
    im_livechat
(L)
    l10n_fr_sale_closing,
    link_tracker,
    lunch
(M)
    mail,
    maintenance,
    mass_mailing,
    membership,
    mrp
(N)
    note
(P)
    payment,
    point_of_sale,
    post_mercury,
    pos_restaurant,
    product,
    project,
    purchase,
    purchase_requisition
(R)
    rating,
    repair,
    resource
(S)
    sale,
    sale_timesheet,
    sales_team,
    stock,
    stock_account,
    stock_landed_costs,
    stock_picking_batch,
    survey
(U)
    utm
(W)
    web,
    website,
    website_blog,
    website_customer,
    website_event_track,
    website_forum,
    website_quote,
    website_sale,
    website_sale_digital,
    website_slides