Include support for STAC access to Digital Earth Australia

[Gilberto Camara]

Describe the requested improvement
We would like to provide R users to access to DEAustralia collections, as part of our missions to provide access to different cloud providers.

According to DEAustralia management, the priority products are as follows:

ARD layers (Landsat, Sentinel-2)

• ga_ls5t_ard_3
• ga_ls7e_ard_3
• ga_ls8c_ard_3
• ga_ls9c_ard_3
• ga_s2am_ard_3
• ga_s2bm_ard_3

Geomedian (current versions; would be good to replace with updated ones when available)

• ga_ls5t_nbart_gm_cyear_3
• ga_ls7e_nbart_gm_cyear_3
• ga_ls8c_nbart_gm_cyear_3

Fractional cover (scenes, calendar year percentiles)

• ga_ls_fc_3
• ga_ls_fc_pc_cyear_3

Water Observations (scenes, annual statistics, multi-year statistics)

• ga_ls_wo_3
  = ga_ls_wo_fq_cyear_3
• ga_ls_wo_fq_myear_3

Land cover

• ga_ls_landcover_class_cyear_2

Intertidal

• ga_s2ls_intertidal_cyear_3

Associated sits API function
create a configuration file for DEAustralia